Warning/Exception for torchtext.data.metrics.bleu_score

[Rajinish0]

🚀 Feature

Motivation

I was working on calculating bleu_score, however, due to a bug in my code I did not realize that my references_corpus wasn't a list of list of words.

Pitch

I think it would be helpful for this function to either give a warning or raise an Exception if the references_corpus is not in the desired format.

Thanks!

Alternatives

Additional context