message: allow 'None' as batch size for TimeFreqLSTMCell
diff: @@ -424,8 +424,8 @@ class TimeFreqLSTMCell(rnn_cell_impl.RNNCell):
  "W_O_diag", shape=[self._num_units], dtype=dtype)
  # initialize the first freq state to be zero
  - m_prev_freq = array_ops.zeros([int(inputs.get_shape()[0]), self._num_units],
  - dtype)
  + m_prev_freq = array_ops.zeros([inputs.get_shape()[0],
  + self._num_units], dtype)
  for fq in range(len(freq_inputs)):
  c_prev = array_ops.slice(state, [0, 2 * fq * self._num_units],
  [-1, self._num_units])
  