diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/DeepTraversal.java b/src/main/java/org/cqfn/astranaut/core/algorithms/DeepTraversal.java
index f24d99f..6244ba6 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/DeepTraversal.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/DeepTraversal.java
@@ -26,7 +26,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Performs a deep traversal of the syntax tree.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/Depth.java b/src/main/java/org/cqfn/astranaut/core/algorithms/Depth.java
index 44a0e8f..f52c8c5 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/Depth.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/Depth.java
@@ -25,7 +25,7 @@
 
 import java.util.HashMap;
 import java.util.Map;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Algorithm for measuring the depth of syntax trees.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilder.java b/src/main/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilder.java
index 6716767..e7dbf2c 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilder.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilder.java
@@ -25,11 +25,11 @@
 
 import java.util.HashMap;
 import java.util.Map;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
 import org.cqfn.astranaut.core.algorithms.mapping.Mapper;
 import org.cqfn.astranaut.core.algorithms.mapping.Mapping;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Builder of difference syntax tree, that is, one that stores changes between two trees.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/Identical.java b/src/main/java/org/cqfn/astranaut/core/algorithms/Identical.java
index bcfa2e9..2471c99 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/Identical.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/Identical.java
@@ -28,8 +28,8 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
-import org.cqfn.astranaut.core.Node;
 import org.cqfn.astranaut.core.algorithms.hash.SimpleHash;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * A class which finds and returns identical nodes in a tree.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/NodeSelector.java b/src/main/java/org/cqfn/astranaut/core/algorithms/NodeSelector.java
index b01c899..96b959f 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/NodeSelector.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/NodeSelector.java
@@ -27,7 +27,7 @@
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.Set;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * An algorithm that selects nodes from a tree based on some criteria.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/PatternBuilder.java b/src/main/java/org/cqfn/astranaut/core/algorithms/PatternBuilder.java
index 012687e..61b55c6 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/PatternBuilder.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/PatternBuilder.java
@@ -25,9 +25,9 @@
 
 import java.util.HashMap;
 import java.util.Map;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.PatternNode;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.PatternNode;
 
 /**
  * Pattern builder.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/ReplaceNode.java b/src/main/java/org/cqfn/astranaut/core/algorithms/ReplaceNode.java
index a9a771b..71cc1c8 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/ReplaceNode.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/ReplaceNode.java
@@ -25,9 +25,9 @@
 
 import java.util.ArrayList;
 import java.util.List;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.utils.Pair;
 
 /**
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/Subtree.java b/src/main/java/org/cqfn/astranaut/core/algorithms/Subtree.java
index f5bbb3d..a8e0f2c 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/Subtree.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/Subtree.java
@@ -28,10 +28,10 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Algorithm that produces a subtree from the original tree.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHash.java b/src/main/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHash.java
index 8057793..36c98d4 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHash.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHash.java
@@ -25,7 +25,7 @@
 
 import java.util.HashMap;
 import java.util.Map;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Computes the absolute hash of a node, that is, a hash that is computed from both the data
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/hash/Hash.java b/src/main/java/org/cqfn/astranaut/core/algorithms/hash/Hash.java
index 421e9ea..962975f 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/hash/Hash.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/hash/Hash.java
@@ -23,7 +23,7 @@
  */
 package org.cqfn.astranaut.core.algorithms.hash;
 
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * An interface that calculates the hash of a node.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/hash/SimpleHash.java b/src/main/java/org/cqfn/astranaut/core/algorithms/hash/SimpleHash.java
index 6ce2b9b..b9457a1 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/hash/SimpleHash.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/hash/SimpleHash.java
@@ -25,7 +25,7 @@
 
 import java.util.HashMap;
 import java.util.Map;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Computes the simple hash of a node, that is, a hash that is computed from the type
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapper.java b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapper.java
index a0c4266..1065e55 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapper.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapper.java
@@ -23,7 +23,7 @@
  */
 package org.cqfn.astranaut.core.algorithms.mapping;
 
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * A mapper that builds correspondences between two trees.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapping.java b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapping.java
index d8a376e..b70c20f 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapping.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/Mapping.java
@@ -25,8 +25,8 @@
 
 import java.util.Map;
 import java.util.Set;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * A mapping from one syntactic tree ('left') to another ('right'), i.e.,
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownAlgorithm.java b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownAlgorithm.java
index 4b8b8d8..47aa08c 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownAlgorithm.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownAlgorithm.java
@@ -28,10 +28,10 @@
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
 import org.cqfn.astranaut.core.algorithms.hash.AbsoluteHash;
 import org.cqfn.astranaut.core.algorithms.hash.Hash;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Top-down mapping algorithm.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapper.java b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapper.java
index d19ff2e..8fb3f25 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapper.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapper.java
@@ -23,7 +23,7 @@
  */
 package org.cqfn.astranaut.core.algorithms.mapping;
 
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Top-down mapper.
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/patching/DefaultPatcher.java b/src/main/java/org/cqfn/astranaut/core/algorithms/patching/DefaultPatcher.java
index f70acc0..c66af78 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/patching/DefaultPatcher.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/patching/DefaultPatcher.java
@@ -24,10 +24,10 @@
 package org.cqfn.astranaut.core.algorithms.patching;
 
 import java.util.Set;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.PatternNode;
-import org.cqfn.astranaut.core.utils.deserializer.ActionList;
+import org.cqfn.astranaut.core.base.ActionList;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.PatternNode;
 
 /**
  * Default algorithm that applies patches, i.e. makes some changes in the syntax tree
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/patching/Patcher.java b/src/main/java/org/cqfn/astranaut/core/algorithms/patching/Patcher.java
index 94f8f2d..dfce342 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/patching/Patcher.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/patching/Patcher.java
@@ -23,8 +23,8 @@
  */
 package org.cqfn.astranaut.core.algorithms.patching;
 
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.PatternNode;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.PatternNode;
 
 /**
  * Interface to an algorithm that applies patches, i.e. makes some changes in the syntax tree
diff --git a/src/main/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcher.java b/src/main/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcher.java
index fca69e5..a7fb3c8 100644
--- a/src/main/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcher.java
+++ b/src/main/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcher.java
@@ -27,15 +27,15 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
-import org.cqfn.astranaut.core.Action;
-import org.cqfn.astranaut.core.Delete;
-import org.cqfn.astranaut.core.Hole;
-import org.cqfn.astranaut.core.Insert;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.PatternNode;
-import org.cqfn.astranaut.core.Replace;
 import org.cqfn.astranaut.core.algorithms.DeepTraversal;
-import org.cqfn.astranaut.core.utils.deserializer.ActionList;
+import org.cqfn.astranaut.core.base.Action;
+import org.cqfn.astranaut.core.base.ActionList;
+import org.cqfn.astranaut.core.base.Delete;
+import org.cqfn.astranaut.core.base.Hole;
+import org.cqfn.astranaut.core.base.Insert;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.PatternNode;
+import org.cqfn.astranaut.core.base.Replace;
 
 /**
  * The matcher matches syntax tree and patterns.
diff --git a/src/main/java/org/cqfn/astranaut/core/Action.java b/src/main/java/org/cqfn/astranaut/core/base/Action.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/Action.java
rename to src/main/java/org/cqfn/astranaut/core/base/Action.java
index 876bfbc..bb06f26 100644
--- a/src/main/java/org/cqfn/astranaut/core/Action.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Action.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * A node that represents an action that can be performed on another node.
diff --git a/src/main/java/org/cqfn/astranaut/core/utils/deserializer/ActionList.java b/src/main/java/org/cqfn/astranaut/core/base/ActionList.java
similarity index 95%
rename from src/main/java/org/cqfn/astranaut/core/utils/deserializer/ActionList.java
rename to src/main/java/org/cqfn/astranaut/core/base/ActionList.java
index 37e6b26..ae1e99e 100644
--- a/src/main/java/org/cqfn/astranaut/core/utils/deserializer/ActionList.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/ActionList.java
@@ -21,15 +21,12 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core.utils.deserializer;
+package org.cqfn.astranaut.core.base;
 
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
 import org.cqfn.astranaut.core.algorithms.DifferenceTreeBuilder;
 
 /**
diff --git a/src/main/java/org/cqfn/astranaut/core/Adapter.java b/src/main/java/org/cqfn/astranaut/core/base/Adapter.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/Adapter.java
rename to src/main/java/org/cqfn/astranaut/core/base/Adapter.java
index 99305dc..770f235 100644
--- a/src/main/java/org/cqfn/astranaut/core/Adapter.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Adapter.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.ArrayList;
 import java.util.List;
diff --git a/src/main/java/org/cqfn/astranaut/core/Builder.java b/src/main/java/org/cqfn/astranaut/core/base/Builder.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/Builder.java
rename to src/main/java/org/cqfn/astranaut/core/base/Builder.java
index 7d345e5..3c64825 100644
--- a/src/main/java/org/cqfn/astranaut/core/Builder.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Builder.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.List;
 
diff --git a/src/main/java/org/cqfn/astranaut/core/ChildDescriptor.java b/src/main/java/org/cqfn/astranaut/core/base/ChildDescriptor.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/ChildDescriptor.java
rename to src/main/java/org/cqfn/astranaut/core/base/ChildDescriptor.java
index 3fa2bde..9ceebbc 100644
--- a/src/main/java/org/cqfn/astranaut/core/ChildDescriptor.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/ChildDescriptor.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * This class describes child node within type descriptor.
diff --git a/src/main/java/org/cqfn/astranaut/core/ChildrenMapper.java b/src/main/java/org/cqfn/astranaut/core/base/ChildrenMapper.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/ChildrenMapper.java
rename to src/main/java/org/cqfn/astranaut/core/base/ChildrenMapper.java
index 6aa9561..32f71d0 100644
--- a/src/main/java/org/cqfn/astranaut/core/ChildrenMapper.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/ChildrenMapper.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.ArrayList;
 import java.util.HashMap;
diff --git a/src/main/java/org/cqfn/astranaut/core/Common.java b/src/main/java/org/cqfn/astranaut/core/base/Common.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/Common.java
rename to src/main/java/org/cqfn/astranaut/core/base/Common.java
index ac34769..29e31a0 100644
--- a/src/main/java/org/cqfn/astranaut/core/Common.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Common.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * Some methods/data that could not be placed to other classes.
diff --git a/src/main/java/org/cqfn/astranaut/core/Converter.java b/src/main/java/org/cqfn/astranaut/core/base/Converter.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/Converter.java
rename to src/main/java/org/cqfn/astranaut/core/base/Converter.java
index d86c338..c08790a 100644
--- a/src/main/java/org/cqfn/astranaut/core/Converter.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Converter.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * Interface for converters that check one rule described in DSL
diff --git a/src/main/java/org/cqfn/astranaut/core/ConvertibleNode.java b/src/main/java/org/cqfn/astranaut/core/base/ConvertibleNode.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/ConvertibleNode.java
rename to src/main/java/org/cqfn/astranaut/core/base/ConvertibleNode.java
index f31baa1..98c14aa 100644
--- a/src/main/java/org/cqfn/astranaut/core/ConvertibleNode.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/ConvertibleNode.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.ArrayList;
 import java.util.List;
diff --git a/src/main/java/org/cqfn/astranaut/core/Delete.java b/src/main/java/org/cqfn/astranaut/core/base/Delete.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/Delete.java
rename to src/main/java/org/cqfn/astranaut/core/base/Delete.java
index 622a3bd..d513793 100644
--- a/src/main/java/org/cqfn/astranaut/core/Delete.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Delete.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import java.util.Collections;
diff --git a/src/main/java/org/cqfn/astranaut/core/DifferenceNode.java b/src/main/java/org/cqfn/astranaut/core/base/DifferenceNode.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/DifferenceNode.java
rename to src/main/java/org/cqfn/astranaut/core/base/DifferenceNode.java
index c145e11..6ff52ae 100644
--- a/src/main/java/org/cqfn/astranaut/core/DifferenceNode.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/DifferenceNode.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.ArrayList;
 import java.util.LinkedList;
diff --git a/src/main/java/org/cqfn/astranaut/core/DifferenceTreeItem.java b/src/main/java/org/cqfn/astranaut/core/base/DifferenceTreeItem.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/DifferenceTreeItem.java
rename to src/main/java/org/cqfn/astranaut/core/base/DifferenceTreeItem.java
index 507393c..749d0eb 100644
--- a/src/main/java/org/cqfn/astranaut/core/DifferenceTreeItem.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/DifferenceTreeItem.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * An element of the difference tree.
diff --git a/src/main/java/org/cqfn/astranaut/core/DraftNode.java b/src/main/java/org/cqfn/astranaut/core/base/DraftNode.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/DraftNode.java
rename to src/main/java/org/cqfn/astranaut/core/base/DraftNode.java
index 3d3cea9..7db289c 100644
--- a/src/main/java/org/cqfn/astranaut/core/DraftNode.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/DraftNode.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.text.CharacterIterator;
 import java.text.StringCharacterIterator;
diff --git a/src/main/java/org/cqfn/astranaut/core/EmptyFragment.java b/src/main/java/org/cqfn/astranaut/core/base/EmptyFragment.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/EmptyFragment.java
rename to src/main/java/org/cqfn/astranaut/core/base/EmptyFragment.java
index f6a1951..d36d2fb 100644
--- a/src/main/java/org/cqfn/astranaut/core/EmptyFragment.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/EmptyFragment.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * The empty fragment.
diff --git a/src/main/java/org/cqfn/astranaut/core/EmptyTree.java b/src/main/java/org/cqfn/astranaut/core/base/EmptyTree.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/EmptyTree.java
rename to src/main/java/org/cqfn/astranaut/core/base/EmptyTree.java
index f05e640..bfecc48 100644
--- a/src/main/java/org/cqfn/astranaut/core/EmptyTree.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/EmptyTree.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Collections;
 import java.util.List;
diff --git a/src/main/java/org/cqfn/astranaut/core/Factory.java b/src/main/java/org/cqfn/astranaut/core/base/Factory.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/Factory.java
rename to src/main/java/org/cqfn/astranaut/core/base/Factory.java
index ccd6d50..34bcbb6 100644
--- a/src/main/java/org/cqfn/astranaut/core/Factory.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Factory.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Map;
 
diff --git a/src/main/java/org/cqfn/astranaut/core/FactorySelector.java b/src/main/java/org/cqfn/astranaut/core/base/FactorySelector.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/FactorySelector.java
rename to src/main/java/org/cqfn/astranaut/core/base/FactorySelector.java
index 86e917f..5de2df8 100644
--- a/src/main/java/org/cqfn/astranaut/core/FactorySelector.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/FactorySelector.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * Interface for factories selection that selects a suitable factory
diff --git a/src/main/java/org/cqfn/astranaut/core/Fragment.java b/src/main/java/org/cqfn/astranaut/core/base/Fragment.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/Fragment.java
rename to src/main/java/org/cqfn/astranaut/core/base/Fragment.java
index 6f1190d..34a5658 100644
--- a/src/main/java/org/cqfn/astranaut/core/Fragment.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Fragment.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * Describes a fragment of source code.
diff --git a/src/main/java/org/cqfn/astranaut/core/Hole.java b/src/main/java/org/cqfn/astranaut/core/base/Hole.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/Hole.java
rename to src/main/java/org/cqfn/astranaut/core/base/Hole.java
index 049a266..efc9ddd 100644
--- a/src/main/java/org/cqfn/astranaut/core/Hole.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Hole.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.List;
 
diff --git a/src/main/java/org/cqfn/astranaut/core/Insert.java b/src/main/java/org/cqfn/astranaut/core/base/Insert.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/Insert.java
rename to src/main/java/org/cqfn/astranaut/core/base/Insert.java
index 4aad07a..c050b88 100644
--- a/src/main/java/org/cqfn/astranaut/core/Insert.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Insert.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import java.util.Collections;
diff --git a/src/main/java/org/cqfn/astranaut/core/Insertion.java b/src/main/java/org/cqfn/astranaut/core/base/Insertion.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/Insertion.java
rename to src/main/java/org/cqfn/astranaut/core/base/Insertion.java
index 5d0697c..d656815 100644
--- a/src/main/java/org/cqfn/astranaut/core/Insertion.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Insertion.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Objects;
 
diff --git a/src/main/java/org/cqfn/astranaut/core/Matcher.java b/src/main/java/org/cqfn/astranaut/core/base/Matcher.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/Matcher.java
rename to src/main/java/org/cqfn/astranaut/core/base/Matcher.java
index 65a2554..cd2fcc4 100644
--- a/src/main/java/org/cqfn/astranaut/core/Matcher.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Matcher.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.List;
 import java.util.Map;
diff --git a/src/main/java/org/cqfn/astranaut/core/Node.java b/src/main/java/org/cqfn/astranaut/core/base/Node.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/Node.java
rename to src/main/java/org/cqfn/astranaut/core/base/Node.java
index 87af1b4..a8462bb 100644
--- a/src/main/java/org/cqfn/astranaut/core/Node.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Node.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import java.util.Iterator;
diff --git a/src/main/java/org/cqfn/astranaut/core/PatternItem.java b/src/main/java/org/cqfn/astranaut/core/base/PatternItem.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/PatternItem.java
rename to src/main/java/org/cqfn/astranaut/core/base/PatternItem.java
index ff19312..7148429 100644
--- a/src/main/java/org/cqfn/astranaut/core/PatternItem.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/PatternItem.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * An element of a pattern.
diff --git a/src/main/java/org/cqfn/astranaut/core/PatternNode.java b/src/main/java/org/cqfn/astranaut/core/base/PatternNode.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/PatternNode.java
rename to src/main/java/org/cqfn/astranaut/core/base/PatternNode.java
index 728fe21..535a8c1 100644
--- a/src/main/java/org/cqfn/astranaut/core/PatternNode.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/PatternNode.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.ArrayList;
 import java.util.List;
diff --git a/src/main/java/org/cqfn/astranaut/core/Position.java b/src/main/java/org/cqfn/astranaut/core/base/Position.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/Position.java
rename to src/main/java/org/cqfn/astranaut/core/base/Position.java
index 678c0ec..3911b26 100644
--- a/src/main/java/org/cqfn/astranaut/core/Position.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Position.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * Represents a position in source code file.
diff --git a/src/main/java/org/cqfn/astranaut/core/Replace.java b/src/main/java/org/cqfn/astranaut/core/base/Replace.java
similarity index 99%
rename from src/main/java/org/cqfn/astranaut/core/Replace.java
rename to src/main/java/org/cqfn/astranaut/core/base/Replace.java
index 7f76983..6c94418 100644
--- a/src/main/java/org/cqfn/astranaut/core/Replace.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Replace.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import java.util.Collections;
diff --git a/src/main/java/org/cqfn/astranaut/core/Source.java b/src/main/java/org/cqfn/astranaut/core/base/Source.java
similarity index 97%
rename from src/main/java/org/cqfn/astranaut/core/Source.java
rename to src/main/java/org/cqfn/astranaut/core/base/Source.java
index 5b62a0c..38485e1 100644
--- a/src/main/java/org/cqfn/astranaut/core/Source.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Source.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 /**
  * Represents a source code file.
diff --git a/src/main/java/org/cqfn/astranaut/core/base/Tree.java b/src/main/java/org/cqfn/astranaut/core/base/Tree.java
index c422b51..4ebde0a 100644
--- a/src/main/java/org/cqfn/astranaut/core/base/Tree.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Tree.java
@@ -23,9 +23,6 @@
  */
 package org.cqfn.astranaut.core.base;
 
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
-
 /**
  * A syntax tree, which represents the hierarchical structure of source code,
  *  depicting the syntactic structure and relationships between code elements.
diff --git a/src/main/java/org/cqfn/astranaut/core/Type.java b/src/main/java/org/cqfn/astranaut/core/base/Type.java
similarity index 98%
rename from src/main/java/org/cqfn/astranaut/core/Type.java
rename to src/main/java/org/cqfn/astranaut/core/base/Type.java
index c01047e..6f4dd0c 100644
--- a/src/main/java/org/cqfn/astranaut/core/Type.java
+++ b/src/main/java/org/cqfn/astranaut/core/base/Type.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.List;
 
diff --git a/src/main/java/org/cqfn/astranaut/core/utils/JsonDeserializer.java b/src/main/java/org/cqfn/astranaut/core/utils/JsonDeserializer.java
index e18adcb..978bf4b 100644
--- a/src/main/java/org/cqfn/astranaut/core/utils/JsonDeserializer.java
+++ b/src/main/java/org/cqfn/astranaut/core/utils/JsonDeserializer.java
@@ -25,9 +25,9 @@
 
 import com.kniazkov.json.Json;
 import com.kniazkov.json.JsonException;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.FactorySelector;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.FactorySelector;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.utils.deserializer.TreeDescriptor;
 
 /**
diff --git a/src/main/java/org/cqfn/astranaut/core/utils/JsonSerializer.java b/src/main/java/org/cqfn/astranaut/core/utils/JsonSerializer.java
index 9aeb346..d9119e5 100644
--- a/src/main/java/org/cqfn/astranaut/core/utils/JsonSerializer.java
+++ b/src/main/java/org/cqfn/astranaut/core/utils/JsonSerializer.java
@@ -27,8 +27,8 @@
 import com.kniazkov.json.JsonObject;
 import java.io.IOException;
 import java.nio.file.InvalidPathException;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Converts a tree to a string that contains JSON object.
diff --git a/src/main/java/org/cqfn/astranaut/core/utils/TreeVisualizer.java b/src/main/java/org/cqfn/astranaut/core/utils/TreeVisualizer.java
index 43a2d9c..3466986 100644
--- a/src/main/java/org/cqfn/astranaut/core/utils/TreeVisualizer.java
+++ b/src/main/java/org/cqfn/astranaut/core/utils/TreeVisualizer.java
@@ -25,7 +25,7 @@
 
 import java.io.File;
 import java.io.IOException;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.exceptions.WrongFileExtension;
 import org.cqfn.astranaut.core.utils.visualizer.DotRender;
 import org.cqfn.astranaut.core.utils.visualizer.ImageRender;
diff --git a/src/main/java/org/cqfn/astranaut/core/utils/deserializer/NodeDescriptor.java b/src/main/java/org/cqfn/astranaut/core/utils/deserializer/NodeDescriptor.java
index 9d95e30..c080d55 100644
--- a/src/main/java/org/cqfn/astranaut/core/utils/deserializer/NodeDescriptor.java
+++ b/src/main/java/org/cqfn/astranaut/core/utils/deserializer/NodeDescriptor.java
@@ -25,13 +25,14 @@
 
 import java.util.ArrayList;
 import java.util.List;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.Delete;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Factory;
-import org.cqfn.astranaut.core.Insert;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Replace;
+import org.cqfn.astranaut.core.base.ActionList;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.Delete;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Factory;
+import org.cqfn.astranaut.core.base.Insert;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Replace;
 
 /**
  * Node descriptor represented as it is stored in the JSON file.
diff --git a/src/main/java/org/cqfn/astranaut/core/utils/deserializer/TreeDescriptor.java b/src/main/java/org/cqfn/astranaut/core/utils/deserializer/TreeDescriptor.java
index 6694e55..84d76ee 100644
--- a/src/main/java/org/cqfn/astranaut/core/utils/deserializer/TreeDescriptor.java
+++ b/src/main/java/org/cqfn/astranaut/core/utils/deserializer/TreeDescriptor.java
@@ -23,10 +23,11 @@
  */
 package org.cqfn.astranaut.core.utils.deserializer;
 
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Factory;
-import org.cqfn.astranaut.core.FactorySelector;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.ActionList;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Factory;
+import org.cqfn.astranaut.core.base.FactorySelector;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Tree descriptor represented as it is stored in the JSON file.
diff --git a/src/main/java/org/cqfn/astranaut/core/utils/visualizer/DotRender.java b/src/main/java/org/cqfn/astranaut/core/utils/visualizer/DotRender.java
index 9b3bc45..5c87322 100644
--- a/src/main/java/org/cqfn/astranaut/core/utils/visualizer/DotRender.java
+++ b/src/main/java/org/cqfn/astranaut/core/utils/visualizer/DotRender.java
@@ -24,9 +24,9 @@
 package org.cqfn.astranaut.core.utils.visualizer;
 
 import java.util.Objects;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Renders a DOT file from a tree.
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/DeepTraversalTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/DeepTraversalTest.java
index 3b76c48..3098de1 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/DeepTraversalTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/DeepTraversalTest.java
@@ -25,8 +25,8 @@
 
 import java.util.List;
 import java.util.Optional;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Node;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/DepthTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/DepthTest.java
index 2e4eb76..15effe8 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/DepthTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/DepthTest.java
@@ -23,7 +23,7 @@
  */
 package org.cqfn.astranaut.core.algorithms;
 
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.example.LittleTrees;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilderTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilderTest.java
index 6420816..86f7b3c 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilderTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilderTest.java
@@ -23,13 +23,13 @@
  */
 package org.cqfn.astranaut.core.algorithms;
 
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
 import org.cqfn.astranaut.core.algorithms.hash.AbsoluteHash;
 import org.cqfn.astranaut.core.algorithms.hash.Hash;
 import org.cqfn.astranaut.core.algorithms.mapping.TopDownMapper;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.example.LittleTrees;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/IdenticalTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/IdenticalTest.java
index d625e1d..de2d8bc 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/IdenticalTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/IdenticalTest.java
@@ -24,8 +24,8 @@
 package org.cqfn.astranaut.core.algorithms;
 
 import java.util.Set;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Node;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/NodeReplacerTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/NodeReplacerTest.java
index 6ef9b72..078c112 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/NodeReplacerTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/NodeReplacerTest.java
@@ -24,9 +24,9 @@
 package org.cqfn.astranaut.core.algorithms;
 
 import java.util.Arrays;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.utils.Pair;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/NodeSelectorTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/NodeSelectorTest.java
index f5c26ee..aea275a 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/NodeSelectorTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/NodeSelectorTest.java
@@ -24,8 +24,8 @@
 package org.cqfn.astranaut.core.algorithms;
 
 import java.util.Set;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Node;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/PatternBuilderTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/PatternBuilderTest.java
index 12b396a..10d37f4 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/PatternBuilderTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/PatternBuilderTest.java
@@ -26,12 +26,12 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Optional;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Hole;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.PatternNode;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Hole;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.PatternNode;
 import org.cqfn.astranaut.core.example.green.Addition;
 import org.cqfn.astranaut.core.example.green.ExpressionStatement;
 import org.cqfn.astranaut.core.example.green.IntegerLiteral;
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/SubtreeTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/SubtreeTest.java
index e55a2e2..322b304 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/SubtreeTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/SubtreeTest.java
@@ -27,9 +27,9 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Node;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHashTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHashTest.java
index 6a8d8f5..ba9939d 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHashTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/hash/AbsoluteHashTest.java
@@ -23,7 +23,7 @@
  */
 package org.cqfn.astranaut.core.algorithms.hash;
 
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.example.LittleTrees;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapperTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapperTest.java
index 8cafae7..7730a7d 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapperTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapperTest.java
@@ -28,9 +28,9 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatcherTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatcherTest.java
index 557bf03..f1babf3 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatcherTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatcherTest.java
@@ -28,14 +28,14 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.PatternNode;
 import org.cqfn.astranaut.core.algorithms.DifferenceTreeBuilder;
 import org.cqfn.astranaut.core.algorithms.PatternBuilder;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.PatternNode;
 import org.cqfn.astranaut.core.example.green.Addition;
 import org.cqfn.astranaut.core.example.green.ExpressionStatement;
 import org.cqfn.astranaut.core.example.green.IntegerLiteral;
diff --git a/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcherTest.java b/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcherTest.java
index 19eb02f..6456dd7 100644
--- a/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcherTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/algorithms/patching/PatternMatcherTest.java
@@ -26,13 +26,13 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.PatternNode;
 import org.cqfn.astranaut.core.algorithms.DifferenceTreeBuilder;
 import org.cqfn.astranaut.core.algorithms.PatternBuilder;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.PatternNode;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/org/cqfn/astranaut/core/ActionTest.java b/src/test/java/org/cqfn/astranaut/core/base/ActionTest.java
similarity index 99%
rename from src/test/java/org/cqfn/astranaut/core/ActionTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/ActionTest.java
index 257bc70..90ccdeb 100644
--- a/src/test/java/org/cqfn/astranaut/core/ActionTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/ActionTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import java.util.Collections;
diff --git a/src/test/java/org/cqfn/astranaut/core/AdapterTest.java b/src/test/java/org/cqfn/astranaut/core/base/AdapterTest.java
similarity index 99%
rename from src/test/java/org/cqfn/astranaut/core/AdapterTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/AdapterTest.java
index 4a38592..2a79b1a 100644
--- a/src/test/java/org/cqfn/astranaut/core/AdapterTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/AdapterTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import java.util.List;
diff --git a/src/test/java/org/cqfn/astranaut/core/BaseNodeTest.java b/src/test/java/org/cqfn/astranaut/core/base/BaseNodeTest.java
similarity index 98%
rename from src/test/java/org/cqfn/astranaut/core/BaseNodeTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/BaseNodeTest.java
index a6c1fb4..a762155 100644
--- a/src/test/java/org/cqfn/astranaut/core/BaseNodeTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/BaseNodeTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Iterator;
 import java.util.NoSuchElementException;
diff --git a/src/test/java/org/cqfn/astranaut/core/ChildrenMapperTest.java b/src/test/java/org/cqfn/astranaut/core/base/ChildrenMapperTest.java
similarity index 99%
rename from src/test/java/org/cqfn/astranaut/core/ChildrenMapperTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/ChildrenMapperTest.java
index f89cb1c..2da8b5d 100644
--- a/src/test/java/org/cqfn/astranaut/core/ChildrenMapperTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/ChildrenMapperTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.ArrayList;
 import java.util.Arrays;
diff --git a/src/test/java/org/cqfn/astranaut/core/ConvertibleNodeTest.java b/src/test/java/org/cqfn/astranaut/core/base/ConvertibleNodeTest.java
similarity index 98%
rename from src/test/java/org/cqfn/astranaut/core/ConvertibleNodeTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/ConvertibleNodeTest.java
index 0b2381a..2c52194 100644
--- a/src/test/java/org/cqfn/astranaut/core/ConvertibleNodeTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/ConvertibleNodeTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import org.cqfn.astranaut.core.example.green.Addition;
diff --git a/src/test/java/org/cqfn/astranaut/core/DifferenceNodeTest.java b/src/test/java/org/cqfn/astranaut/core/base/DifferenceNodeTest.java
similarity index 99%
rename from src/test/java/org/cqfn/astranaut/core/DifferenceNodeTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/DifferenceNodeTest.java
index 9f22f31..162652f 100644
--- a/src/test/java/org/cqfn/astranaut/core/DifferenceNodeTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/DifferenceNodeTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import org.cqfn.astranaut.core.example.LittleTrees;
 import org.cqfn.astranaut.core.example.green.GreenFactory;
diff --git a/src/test/java/org/cqfn/astranaut/core/DraftNodeTest.java b/src/test/java/org/cqfn/astranaut/core/base/DraftNodeTest.java
similarity index 99%
rename from src/test/java/org/cqfn/astranaut/core/DraftNodeTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/DraftNodeTest.java
index 03b6f3e..04f710b 100644
--- a/src/test/java/org/cqfn/astranaut/core/DraftNodeTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/DraftNodeTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import java.util.Arrays;
 import java.util.Collections;
diff --git a/src/test/java/org/cqfn/astranaut/core/HoleTest.java b/src/test/java/org/cqfn/astranaut/core/base/HoleTest.java
similarity index 98%
rename from src/test/java/org/cqfn/astranaut/core/HoleTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/HoleTest.java
index bc8c3ed..fcb6102 100644
--- a/src/test/java/org/cqfn/astranaut/core/HoleTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/HoleTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import org.cqfn.astranaut.core.example.green.IntegerLiteral;
 import org.junit.jupiter.api.Assertions;
diff --git a/src/test/java/org/cqfn/astranaut/core/PatternNodeTest.java b/src/test/java/org/cqfn/astranaut/core/base/PatternNodeTest.java
similarity index 98%
rename from src/test/java/org/cqfn/astranaut/core/PatternNodeTest.java
rename to src/test/java/org/cqfn/astranaut/core/base/PatternNodeTest.java
index 5a54323..18adfc6 100644
--- a/src/test/java/org/cqfn/astranaut/core/PatternNodeTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/PatternNodeTest.java
@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cqfn.astranaut.core;
+package org.cqfn.astranaut.core.base;
 
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
diff --git a/src/test/java/org/cqfn/astranaut/core/base/TreeTest.java b/src/test/java/org/cqfn/astranaut/core/base/TreeTest.java
index 8834154..60a8c22 100644
--- a/src/test/java/org/cqfn/astranaut/core/base/TreeTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/base/TreeTest.java
@@ -25,13 +25,6 @@
 
 import java.util.Collections;
 import java.util.List;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
diff --git a/src/test/java/org/cqfn/astranaut/core/example/LittleTrees.java b/src/test/java/org/cqfn/astranaut/core/example/LittleTrees.java
index c2f8867..cdabc96 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/LittleTrees.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/LittleTrees.java
@@ -25,11 +25,11 @@
 
 import java.util.Arrays;
 import java.util.Collections;
-import org.cqfn.astranaut.core.DifferenceNode;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Insertion;
-import org.cqfn.astranaut.core.Node;
 import org.cqfn.astranaut.core.algorithms.DifferenceTreeBuilder;
+import org.cqfn.astranaut.core.base.DifferenceNode;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Insertion;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.example.green.Addition;
 import org.cqfn.astranaut.core.example.green.ExpressionStatement;
 import org.cqfn.astranaut.core.example.green.IntegerLiteral;
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/Addition.java b/src/test/java/org/cqfn/astranaut/core/example/green/Addition.java
index 184a3a1..df340ec 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/Addition.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/Addition.java
@@ -29,13 +29,13 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.ChildrenMapper;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.ChildrenMapper;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Node that describes the 'Addition' type.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/Expression.java b/src/test/java/org/cqfn/astranaut/core/example/green/Expression.java
index c5dd350..c123291 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/Expression.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/Expression.java
@@ -23,7 +23,7 @@
  */
 package org.cqfn.astranaut.core.example.green;
 
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Node that describes the 'Expression' type.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionList.java b/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionList.java
index 652f8fe..611d00f 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionList.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionList.java
@@ -27,12 +27,12 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Node that describes the 'ExpressionList' type.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionStatement.java b/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionStatement.java
index e3e3c8b..23b0bc7 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionStatement.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/ExpressionStatement.java
@@ -30,13 +30,13 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.ChildrenMapper;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.ChildrenMapper;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 import org.cqfn.astranaut.core.utils.ListUtils;
 
 /**
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/GreenFactory.java b/src/test/java/org/cqfn/astranaut/core/example/green/GreenFactory.java
index 2084b4c..334f0d4 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/GreenFactory.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/GreenFactory.java
@@ -28,8 +28,8 @@
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
-import org.cqfn.astranaut.core.Factory;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Factory;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Factory that creates 'green' nodes.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/IntegerLiteral.java b/src/test/java/org/cqfn/astranaut/core/example/green/IntegerLiteral.java
index 582d303..2a6ea08 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/IntegerLiteral.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/IntegerLiteral.java
@@ -29,12 +29,12 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Node that describes the 'IntegerLiteral' type.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/Return.java b/src/test/java/org/cqfn/astranaut/core/example/green/Return.java
index d92dfeb..353a80a 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/Return.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/Return.java
@@ -30,13 +30,13 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.ChildrenMapper;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.ChildrenMapper;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 import org.cqfn.astranaut.core.utils.ListUtils;
 
 /**
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/SimpleAssignment.java b/src/test/java/org/cqfn/astranaut/core/example/green/SimpleAssignment.java
index cd46092..71d496f 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/SimpleAssignment.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/SimpleAssignment.java
@@ -30,13 +30,13 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.ChildrenMapper;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.ChildrenMapper;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 import org.cqfn.astranaut.core.utils.ListUtils;
 
 /**
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/Statement.java b/src/test/java/org/cqfn/astranaut/core/example/green/Statement.java
index 7c05212..dde3cfe 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/Statement.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/Statement.java
@@ -23,7 +23,7 @@
  */
 package org.cqfn.astranaut.core.example.green;
 
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Node that describes the 'Statement' type.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/StatementBlock.java b/src/test/java/org/cqfn/astranaut/core/example/green/StatementBlock.java
index f65eae2..ce57c2f 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/StatementBlock.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/StatementBlock.java
@@ -31,12 +31,12 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Node that describes the 'StatementBlock' type.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/green/Variable.java b/src/test/java/org/cqfn/astranaut/core/example/green/Variable.java
index 31e0e63..a88ea28 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/green/Variable.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/green/Variable.java
@@ -29,12 +29,12 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 
 /**
  * Node that describes the 'Variable' type.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher0.java b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher0.java
index 8d103b5..bae692c 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher0.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher0.java
@@ -25,8 +25,8 @@
 
 import java.util.List;
 import java.util.Map;
-import org.cqfn.astranaut.core.Matcher;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Matcher;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Matcher for the subtree returned by the 'js' language parser.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher1.java b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher1.java
index 9a36e5d..90b0b94 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher1.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher1.java
@@ -25,8 +25,8 @@
 
 import java.util.List;
 import java.util.Map;
-import org.cqfn.astranaut.core.Matcher;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Matcher;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Matcher for the subtree returned by the 'js' language parser.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher2.java b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher2.java
index 947b96d..7ed144e 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher2.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Matcher2.java
@@ -25,8 +25,8 @@
 
 import java.util.List;
 import java.util.Map;
-import org.cqfn.astranaut.core.Matcher;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Matcher;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Matcher for the subtree returned by the 'js' language parser.
diff --git a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Rule0.java b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Rule0.java
index 0f283a8..3e83a1e 100644
--- a/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Rule0.java
+++ b/src/test/java/org/cqfn/astranaut/core/example/javascript/rules/Rule0.java
@@ -26,11 +26,11 @@
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.Converter;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Factory;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.Converter;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Factory;
+import org.cqfn.astranaut.core.base.Node;
 
 /**
  * Converter describing DSL conversion rule.
diff --git a/src/test/java/org/cqfn/astranaut/core/utils/DotRenderTest.java b/src/test/java/org/cqfn/astranaut/core/utils/DotRenderTest.java
index 559158a..ccedbdb 100644
--- a/src/test/java/org/cqfn/astranaut/core/utils/DotRenderTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/utils/DotRenderTest.java
@@ -26,9 +26,9 @@
 import java.io.IOException;
 import java.util.LinkedList;
 import java.util.List;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.utils.visualizer.DotRender;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
diff --git a/src/test/java/org/cqfn/astranaut/core/utils/JsonDeserializerTest.java b/src/test/java/org/cqfn/astranaut/core/utils/JsonDeserializerTest.java
index 5a84ef0..2ada442 100644
--- a/src/test/java/org/cqfn/astranaut/core/utils/JsonDeserializerTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/utils/JsonDeserializerTest.java
@@ -26,9 +26,9 @@
 import java.util.Collections;
 import java.util.Map;
 import java.util.TreeMap;
-import org.cqfn.astranaut.core.Factory;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Factory;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 import org.cqfn.astranaut.core.example.LittleTrees;
 import org.cqfn.astranaut.core.example.green.Addition;
 import org.cqfn.astranaut.core.example.green.GreenFactory;
diff --git a/src/test/java/org/cqfn/astranaut/core/utils/JsonSerializerTest.java b/src/test/java/org/cqfn/astranaut/core/utils/JsonSerializerTest.java
index 55e9598..f287c41 100644
--- a/src/test/java/org/cqfn/astranaut/core/utils/JsonSerializerTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/utils/JsonSerializerTest.java
@@ -28,14 +28,14 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
-import org.cqfn.astranaut.core.Builder;
-import org.cqfn.astranaut.core.ChildDescriptor;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.EmptyFragment;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Fragment;
-import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.Type;
+import org.cqfn.astranaut.core.base.Builder;
+import org.cqfn.astranaut.core.base.ChildDescriptor;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.EmptyFragment;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Fragment;
+import org.cqfn.astranaut.core.base.Node;
+import org.cqfn.astranaut.core.base.Type;
 import org.cqfn.astranaut.core.example.LittleTrees;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
diff --git a/src/test/java/org/cqfn/astranaut/core/utils/TreeVisualizerTest.java b/src/test/java/org/cqfn/astranaut/core/utils/TreeVisualizerTest.java
index c20a56b..8670731 100644
--- a/src/test/java/org/cqfn/astranaut/core/utils/TreeVisualizerTest.java
+++ b/src/test/java/org/cqfn/astranaut/core/utils/TreeVisualizerTest.java
@@ -27,9 +27,9 @@
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.Arrays;
-import org.cqfn.astranaut.core.DraftNode;
-import org.cqfn.astranaut.core.EmptyTree;
-import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.base.DraftNode;
+import org.cqfn.astranaut.core.base.EmptyTree;
+import org.cqfn.astranaut.core.base.Node;
 import org.cqfn.astranaut.core.exceptions.WrongFileExtension;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;