code: def remove(self, x):
      
      with tf.name_scope("pad_reduce/remove"):
        x_shape = x.get_shape().as_list()
        x = tf.gather_nd(
            x,
            indices=self.nonpad_ids,
        )
        if not tf.executing_eagerly():
          # This is a hack but for some reason, gather_nd return a tensor of
          # undefined shape, so the shape is set up manually
          x.set_shape([None] + x_shape[1:])
      return x
docs: Remove padding from the given tensor.
  
      Args:
        x (tf.Tensor): of shape [dim_origin,...]
  
      Returns:
        a tensor of shape [dim_compressed,...] with dim_compressed <= dim_origin