1class NodeVisitor: 2 def get_visitor(self, node): ... 3 def visit(self, node, *args, **kwargs): ... 4 def generic_visit(self, node, *args, **kwargs): ... 5 6class NodeTransformer(NodeVisitor): 7 def generic_visit(self, node, *args, **kwargs): ... 8 def visit_list(self, node, *args, **kwargs): ... 9