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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def save_graph_to_file(graph_file_name, module_spec, class_count):
 """Saves an graph to file, creating a valid quantized one if necessary."""

  sess, _, _, _, _, _ = build_eval_session(module_spec, class_count)
  graph = sess.graph

  output_graph_def = tf.graph_util.convert_variables_to_constants(
      sess, graph.as_graph_def(), [FLAGS.final_tensor_name])

  with tf.gfile.GFile(graph_file_name, 'wb') as f:
    f.write(output_graph_def.SerializeToString())