import tensorflow as tf

    all_features.update(self._context_keys_to_features)
    all_features.update(self._sequence_keys_to_features)

    # Reshape non-sparse elements just once:
    for k, value in all_features.items():
      if isinstance(value, tf.FixedLenFeature):
        example[k] = tf.reshape(example[k], value.shape)

    if not items:
      items = self._items_to_handlers.keys()

    outputs = []
