docs: def AddChild(self, path_info):
      """Makes the path aware of some child."""
  
      if self._path_type != path_info.path_type:
        message = "Incompatible path types: `%s` and `%s`"
        raise ValueError(message % (self._path_type, path_info.path_type))
      if self._components != path_info.components[:-1]:
        message = "Incompatible path components, expected `%s` but got `%s`"
        raise ValueError(message % (self._components, path_info.components[:-1]))
  
      self._children.add(path_info.GetPathID())