Traceback (most recent call last): File "astgraphforsympy.py", line 86, in <module> print get_func_calls(tree) File "astgraphforsympy.py", line 48, in get_func_calls for node in ast.walk(tree): File "C:\Python27\lib\ast.py", line 213, in walk todo.extend(iter_child_nodes(node)) File "C:\Python27\lib\ast.py", line 178, in iter_child_nodes for name, field in iter_fields(node): File "C:\Python27\lib\ast.py", line 166, in iter_fields for field in node._fields: AttributeError: Module instance has no attribute '_fields' -- https://mail.python.org/mailman/listinfo/python-list