code: def _indices(self):
          
          path = self.parent
          layer = path.parent
          for path_index in range(len(layer.paths)):
              if path == layer.paths[path_index]:
                  for node_index in range(len(path.nodes)):
                      if self == path.nodes[node_index]:
                          return Point(path_index, node_index)
          return None
docs: Find the path_index and node_index that identify the given node.