import tensorflow as tf

                    trainable=True
                )

            self.ch_len = tf.reshape(tf.reduce_sum(
                tf.cast(tf.cast(self.ch, tf.bool), tf.int32), axis=2), [-1])
            self.qh_len = tf.reshape(tf.reduce_sum(
                tf.cast(tf.cast(self.qh, tf.bool), tf.int32), axis=2), [-1])

