code: def load_graph(frozen_graph_filename, namespace_prefix="", placeholders=None):
      
      # Load graph def from protobuff and import the definition
      with tf.gfile.GFile(frozen_graph_filename, "rb") as f:
          graph_def = tf.GraphDef()
          graph_def.ParseFromString(f.read())
  
      if placeholders is None:
          with tf.Graph().as_default() as graph:
              tf.import_graph_def(graph_def, name=namespace_prefix)
      else:
          with tf.Graph().as_default() as graph:
              tf.import_graph_def(graph_def, input_map=placeholders, name=namespace_prefix)
      return graph
docs: Loads a frozen graph from a *.pb file.
      :param frozen_graph_filename: The file which graph to load.
      :param namespace_prefix: A namespace for your graph to live in. This is useful when having multiple models.
      :param placeholders: A dict containing the new placeholders that replace the old inputs.
      :return: The graph that can now be passed to a session when creating it.