SentiWordNet can be imported like this:
>>> from nltk.corpus import sentiwordnet as swn
>>> breakdown = swn.senti_synset('breakdown.n.03')
>>> print(breakdown)
<breakdown.n.03: PosScore=0.0 NegScore=0.25>
>>> breakdown.pos_score()
0.0
>>> breakdown.neg_score()
0.25
>>> breakdown.obj_score()
0.75
>>> list(swn.senti_synsets('slow')) # doctest: +NORMALIZE_WHITESPACE [SentiSynset('decelerate.v.01'), SentiSynset('slow.v.02'), SentiSynset('slow.v.03'), SentiSynset('slow.a.01'), SentiSynset('slow.a.02'), SentiSynset('slow.a.04'), SentiSynset('slowly.r.01'), SentiSynset('behind.r.03')]>>> happy = swn.senti_synsets('happy', 'a')>>> all = swn.all_senti_synsets()