Wordnet common hypernyms lookup speedup and refactoring
Wordnet common hypernyms lookup speedup and refactoring
Wordnet common hypernyms lookup speedup and refactoring
Merge branch 'WordnetSpeed' of https://github.com/watercrossing/nltk into develop
merging https://github.com/nltk/nltk/pull/563, memoizing the hypernyms for efficiency; changed _allHypernymsSet to _all_hypernyms; tweaked doctests