code: private void associateClones(Node n, Node snapshot) {
      // TODO(johnlenz): determine if MODULE_BODY is useful here.
      if (n.isRoot() || NodeUtil.isChangeScopeRoot(n)) {
        clonesByCurrent.put(n, snapshot);
      }
  
      Node child = n.getFirstChild();
      Node snapshotChild = snapshot.getFirstChild();
      while (child != null) {
        associateClones(child, snapshotChild);
        child = child.getNext();
        snapshotChild = snapshotChild.getNext();
      }
    }
docs: Given an AST and its copy, map the root node of each scope of main to the
  corresponding root node of clone