old_contents: # Copyright 2017 The TensorFlow Authors. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # =============================================================================
  """Provides a proper python API for the symbols exported through swig."""
  
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  from tensorflow.core.framework import graph_pb2
  from tensorflow.core.protobuf import config_pb2
  from tensorflow.python import pywrap_tensorflow as tf_opt
  from tensorflow.python.grappler import cluster as gcluster
  
  
  def OptimizeGraph(config_proto,
                    metagraph,
                    verbose=True,
                    graph_id=b'graph_to_optimize',
                    cluster=None):
    """Optimize the provided metagraph."""
    if not isinstance(config_proto, config_pb2.ConfigProto):
      raise TypeError('Expected config_proto to be a ConfigProto, saw type %s' %
                      type(config_proto))
    if cluster is None:
      cluster = gcluster.Cluster()
    ret_from_swig = tf_opt.TF_OptimizeGraph(cluster.tf_cluster,
                                            config_proto.SerializeToString(),
                                            metagraph.SerializeToString(),
                                            verbose, graph_id)
    if ret_from_swig is None:
      return None
    out_graph = graph_pb2.GraphDef().FromString(ret_from_swig)
    return out_graph
  
new_contents: # Copyright 2017 The TensorFlow Authors. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # =============================================================================
  """Provides a proper python API for the symbols exported through swig."""
  
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  from tensorflow.core.framework import graph_pb2
  from tensorflow.core.protobuf import config_pb2
  from tensorflow.python import pywrap_tensorflow as tf_opt
  from tensorflow.python.grappler import cluster as gcluster
  
  
  def OptimizeGraph(config_proto,
                    metagraph,
                    verbose=True,
                    graph_id=b'graph_to_optimize',
                    cluster=None):
    """Optimize the provided metagraph.
  
    For best results, the signature_def field in `metagraph` should be populated
    with information about input (feed) and output (fetch) tensors.
    """
    if not isinstance(config_proto, config_pb2.ConfigProto):
      raise TypeError('Expected config_proto to be a ConfigProto, saw type %s' %
                      type(config_proto))
    if cluster is None:
      cluster = gcluster.Cluster()
    ret_from_swig = tf_opt.TF_OptimizeGraph(cluster.tf_cluster,
                                            config_proto.SerializeToString(),
                                            metagraph.SerializeToString(),
                                            verbose, graph_id)
    if ret_from_swig is None:
      return None
    out_graph = graph_pb2.GraphDef().FromString(ret_from_swig)
    return out_graph
  
subject: Add comment about the need to set feeds and fetches in signature_def when calling tf_optimizer.