def synset(self, synset_repr):
parts = synset_repr.split('<STR_LIT:.>')<EOL>if len(parts) != <NUM_LIT:3>:<EOL><INDENT>return None<EOL><DEDENT>lemma, pos, sensenum = parts<EOL>if not sensenum.isdigit() or pos not in SHORT_POS_TO_LONG:<EOL><INDENT>return None<EOL><DEDENT>sensenum   = int(sensenum, <NUM_LIT:10>)<EOL>pos        = SHORT_POS_TO_LONG[pos]<EOL>lemma_dict = self._mongo_db.lexunits.find_one({'<STR_LIT>': lemma,<EOL>'<STR_LIT>': pos,<EOL>'<STR_LIT>':    sensenum})<EOL>if lemma_dict:<EOL><INDENT>return Lemma(self, lemma_dict).synset<EOL><DEDENT>
Looks up a synset in GermaNet using its string representation.

Arguments:
- `synset_repr`: a unicode string containing the lemma, part
  of speech, and sense number of the first lemma of the synset

>>> gn.synset(u'funktionieren.v.2')
Synset(funktionieren.v.2)