diff --git a/openrewrite/src/core/markers.ts b/openrewrite/src/core/markers.ts
index c5e76741..022ed8d3 100644
--- a/openrewrite/src/core/markers.ts
+++ b/openrewrite/src/core/markers.ts
@@ -1,7 +1,7 @@
 import {random_id, UUID} from "./tree";
 
 export interface Marker {
-    id(): UUID;
+    get id(): UUID;
 
     withId(id: UUID): Marker;
 }
@@ -17,7 +17,7 @@ export class Markers {
         this._markers = markers;
     }
 
-    public id(): UUID {
+    public get id(): UUID {
         return this._id;
     }
 
@@ -25,7 +25,7 @@ export class Markers {
         return this._id === id ? this : new Markers(id, this._markers);
     }
 
-    public markers(): Marker[] {
+    public get markers(): Marker[] {
         return this._markers;
     }
 
diff --git a/openrewrite/src/core/tree.ts b/openrewrite/src/core/tree.ts
index 88679ed6..53f298a7 100644
--- a/openrewrite/src/core/tree.ts
+++ b/openrewrite/src/core/tree.ts
@@ -1,4 +1,5 @@
 import {v4 as uuidv4} from 'uuid';
+import {Markers} from "./markers";
 
 export type UUID = string;
 
@@ -6,7 +7,41 @@ export const random_id = (): UUID => {
     return uuidv4();
 }
 
+export interface Tree {
+    get id(): UUID;
+
+    withId(id: UUID): Tree;
+
+    get markers(): Markers;
+
+    withMarkers(markers: Markers): Tree;
+
+    isAcceptable<P>(v: TreeVisitor<Tree, P>, p: P): boolean;
+
+    accept<R extends Tree, P>(v: TreeVisitor<R, P>, p: P): R | null;
+}
+
+export abstract class TreeVisitor<T extends Tree, P> {
+    private _cursor: Cursor;
+
+    protected constructor() {
+        this._cursor = new Cursor(null, Cursor.ROOT_VALUE);
+    }
+
+    public get cursor(): Cursor {
+        return this._cursor;
+    }
+
+    public set cursor(cursor: Cursor) {
+        this._cursor = cursor;
+    }
+
+    abstract visit(tree: Tree | null, p: P): T | null;
+}
+
 export class Cursor {
+    public static ROOT_VALUE: String = "root";
+
     private readonly _parent: Cursor | null;
     private readonly _value: Object;
     private _messages: Map<string, Object>;
@@ -17,7 +52,7 @@ export class Cursor {
         this._messages = new Map<string, Object>();
     }
 
-    public parent(): Cursor | null {
+    public get parent(): Cursor | null {
         return this._parent;
     }
 
@@ -29,9 +64,3 @@ export class Cursor {
         return new Cursor(this._parent === null ? null : this._parent.fork(), this.value);
     }
 }
-
-export interface Tree {
-    id(): UUID;
-
-    withId(id: UUID): Tree;
-}