title: cannot import name 'string_int_label_map_pb2'
body: <p>My goal is to run tensorflow object detection API and followed the steps in the installation.</p>
  
  <p>I install the tensorflow object detection API and protobuf.
  I have also added the path to protobuf.
  But the following error shoots up:</p>
  
  <pre><code>ImportError: cannot import name 'string_int_label_map_pb2'
  </code></pre>
  
  <p>Installed protobuf :</p>
  
  <pre><code>%%bash
  cd models/research
  protoc object_detection/protos/*.proto --python_out=.
  </code></pre>
  
  <p>A block of code containing the error import statements:</p>
  
  <pre><code>from object_detection.utils import ops as utils_ops
  from object_detection.utils import label_map_util
  from object_detection.utils import visualization_utils as vis_util
  </code></pre>