code: def _unpack_cell(cell):
      """Unpack the cells because the stack_bidirectional_dynamic_rnn
      expects a list of cells, one per layer."""
      if isinstance(cell, tf.contrib.rnn.MultiRNNCell):
          return cell._cells  # pylint: disable=W0212
      else:
          return [cell]
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import copy
  import tensorflow
  from tensorflow.contrib.rnn.python.ops import rnn
  from seq2seq.encoders.encoder import Encoder, EncoderOutput
  from seq2seq.training import utils
label_desc: Use image node_id 1 for calling a global function with example usage: _unpack_cell(cell) and returns: cell, list