Converting Atom.is_error() in atoms.py into atom_is_error() in ba…

…se.py, because error expressions are not part of the core MeTTa spec

python/hyperon/atoms.py

@@ -27,9 +27,6 @@ def __repr__(self):
         """Renders a human-readable text description of the Atom."""
         return hp.atom_to_str(self.catom)
 
-    def is_error(self):
-        return hp.atom_is_error(self.catom)
-
     def get_type(self):
         """Gets the type of the current Atom instance"""
         return hp.atom_get_type(self.catom)

python/hyperon/base.py

@@ -485,3 +485,7 @@ def get_atom_types(gnd_space, atom):
     """Provides all types for the given Atom in the context of the given Space."""
     result = hp.get_atom_types(gnd_space.cspace, atom.catom)
     return [Atom._from_catom(catom) for catom in result]
+
+def atom_is_error(atom):
+    """Checks whether an Atom is an error expression"""
+    return hp.atom_is_error(atom.catom)

repl/src/py_shim.py

@@ -49,7 +49,7 @@ def get_config_atom(metta, config_name):
     result = metta.run("!(get-state " + config_name + ")")
     try:
         atom = result[0][0]
-        if (atom.is_error()):
+        if (atom_is_error(atom)):
             return None
         else:
             return atom