code: def add_graph(self, run_key, device_name, graph_def, debug=False):
      
      graph_dict = (self._run_key_to_debug_graphs if debug else
                    self._run_key_to_original_graphs)
      if not run_key in graph_dict:
        graph_dict[run_key] = dict()  # Mapping device_name to GraphDef.
      graph_dict[run_key][tf.compat.as_str(device_name)] = (
          debug_graphs_helper.DebugGraphWrapper(graph_def))
docs: Add a GraphDef.
  
      Args:
        run_key: A key for the run, containing information about the feeds,
          fetches, and targets.
        device_name: The name of the device that the `GraphDef` is for.
        graph_def: An instance of the `GraphDef` proto.
        debug: Whether `graph_def` consists of the debug ops.