nltk/nltk — pull request #520 by huderlem (2013-10-27 20:18:17+00:00)
Title: Implemented span_tokenize() method for PunktWordTokenizer.

I noticed that the span_tokenize() method was unimplemented in the PunktWordTokenizer class. I modeled the implementation of this method after the span_tokenize() method in the PunktSentenceTokenizer class.