Created by: lcy-seso

Weight normalization is used in Facebook's convS2S model. We have not considered how to implement it yet.

But, right now this may not be the top priority. Weight normalization can be directly implemented by using the norm_op. We can later determine how to better wrap this up(provide a convenient wrapper for users).

The author's implementation https://github.com/TimSalimans/weight_norm/blob/master/nn.py#L220 .