import tensorflow as tf

                                                           dtype=tf.float32,
                                                           initializer=tf.constant_initializer(
                                                               self.vocab.char_embeddings[2:],
                                                               dtype=tf.float32),
                                                           trainable=False)
                self.char_pad_unk_mat = tf.get_variable("char_unk_pad",
                                                        [2, self.pretrained_char_mat.get_shape()[1]],
                                                        dtype=tf.float32,
                                                        initializer=tf.constant_initializer(
                                                            self.vocab.char_embeddings[:2],
                                                            dtype=tf.float32),
                                                        trainable=True)

                self.char_mat = tf.concat([self.char_pad_unk_mat, self.pretrained_char_mat], axis=0)

            else:
