example turn based architecture

self.is_first_turn = tf.placeholder(tf.bool)

logger.debug('We get input features for each turn, to represent dialog, we need to store the state between the turns')
dialog_state_before_turn = tf.get_variable('dialog_state_before_turn', initializer=encoder_cell.zero_state(c.batch_size))
dialog_state_before_turn = control_flow_ops.cond(self.is_first_turn,
                                          lambda: encoder_cell.zero_state(c.batch_size),
                                          lambda: dialog_state_before_turn)
logger.debug('Initialization of encoder inputs and control flow took  %.2f s.', inpt_timer())
words_hidden_feat, dialog_state_after_turn = tf.nn.rnn(encoder_cell, embedded_inputs, 
        initial_state=dialog_state_before_turn, sequence_length=turn_len)
tf.assign(dialog_state_before_turn, dialog_state_after_turn)