message: Add missing python import
diff: @@ -67,6 +67,7 @@ def model_to_dot(model, show_shapes=False, show_layer_names=True, rankdir='TB'):
  """
  from tensorflow.python.keras.layers.wrappers import Wrapper
  from tensorflow.python.keras.models import Sequential
  + from tensorflow.python.util import nest
  _check_pydot()
  dot = pydot.Dot()
  