message: Fix TypeError when using tf.keras.utils.plot_model
  This fix fixes the issue raised in 24622
  where a TypeError was raised when using tf.keras.utils.plot_model.
  This fix fixes 24622.
diff: @@ -120,7 +120,7 @@ def model_to_dot(model, show_shapes=False, show_layer_names=True, rankdir='TB'):
  for i, node in enumerate(layer._inbound_nodes):
  node_key = layer.name + '_ib-' + str(i)
  if node_key in model._network_nodes: # pylint: disable=protected-access
  - for inbound_layer in node.inbound_layers:
  + for inbound_layer in nest.flatten(node.inbound_layers):
  inbound_layer_id = str(id(inbound_layer))
  layer_id = str(id(layer))
  dot.add_edge(pydot.Edge(inbound_layer_id, layer_id))
  