>>> input_word_emb.shape
TensorShape([Dimension(None), Dimension(25), Dimension(256)])

>>> tf.transpose(input_word_emb).shape
TensorShape([Dimension(256), Dimension(25), Dimension(None)])

>>> tf.transpose(input_word_emb, [0,2,1]).shape
TensorShape([Dimension(None), Dimension(256), Dimension(25)])