Length penalty for nn.beam_search.BeamSearch

[nicola-decao]

I see that in nn.beam_search.BeamSearch there is no way to specify the length penalty. How is implemented now? Is it using length penalty or not?

I imagine that the desiderata should be to use a simple penalty but I cannot understand from the code if that is the case.

[epwalsh]

There is not a length penalty at the moment, but this option would be a welcome addition to the library.