Get the session.run() metadata associated with a TensorFlow run and tag.

    Args:
      run: A string name of a TensorFlow run.
      tag: A string name of the tag associated with a particular session.run().

    Raises:
      KeyError: If the run is not found, or the tag is not available for the
        given run.

    Returns:
      The metadata in the form of `RunMetadata` protobuf data structure.

def RunMetadata(self, run, tag):
    """Get the session.run() metadata associated with a TensorFlow run and tag.

    Args:
      run: A string name of a TensorFlow run.
      tag: A string name of the tag associated with a particular session.run().

    Raises:
      KeyError: If the run is not found, or the tag is not available for the
        given run.

    Returns:
      The metadata in the form of `RunMetadata` protobuf data structure.
    """
    accumulator = self.GetAccumulator(run)
    return accumulator.RunMetadata(tag)