message: Flatten output_types and output_shapes
diff: @@ -18,6 +18,7 @@ from __future__ import division
  from __future__ import print_function
  from tensorflow.python.data.ops import dataset_ops
  +from tensorflow.python.data.util import nest
  from tensorflow.python.data.util import structure
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  @@ -52,7 +53,10 @@ class LMDBDataset(dataset_ops.DatasetSource):
  filenames, dtype=dtypes.string, name="filenames")
  def _as_variant_tensor(self):
  - return lmdb_ops.lmdb_dataset( self._filenames)
  + return lmdb_ops.lmdb_dataset(
  + self._filenames,
  + nest.flatten(self.output_types),
  + nest.flatten(self.output_shapes))
  @property
  def output_classes(self):
  