'Return lemma object that matches the name'

def lemma(self, name, lang=u'eng'):

    separator = SENSENUM_RE.search(name).start()
    (synset_name, lemma_name) = (name[:(separator + 3)], name[(separator + 4):])
    synset = self.synset(synset_name)
    for lemma in synset.lemmas(lang):
        if (lemma._name == lemma_name):
            return lemma
    raise WordNetError((u'no    lemma    %r    in    %r' % (lemma_name, synset_name)))
