message: Add expected keys to predictor exception if unexpected key detected.
diff: # See the License for the specific language governing permissions and
  # limitations under the License.
  # ==============================================================================
  -
  """Abstract base class for all predictors."""
  from __future__ import absolute_import
  @@ -66,8 +65,9 @@ class Predictor(object):
  expected_keys = set(self.feed_tensors.keys())
  unexpected_keys = input_keys - expected_keys
  if unexpected_keys:
  - raise ValueError('Got unexpected keys in input_dict: {}'.format(
  - unexpected_keys))
  + raise ValueError(
  + 'Got unexpected keys in input_dict: {}\nexpected: {}'.format(
  + unexpected_keys, expected_keys))
  feed_dict = {}
  for key in self.feed_tensors.keys():
  