def lemmas(self, lemma, pos = None):
if pos is not None:<EOL><INDENT>if pos not in SHORT_POS_TO_LONG:<EOL><INDENT>return None<EOL><DEDENT>pos         = SHORT_POS_TO_LONG[pos]<EOL>lemma_dicts = self._mongo_db.lexunits.find({'<STR_LIT>': lemma,<EOL>'<STR_LIT>': pos})<EOL><DEDENT>else:<EOL><INDENT>lemma_dicts = self._mongo_db.lexunits.find({'<STR_LIT>': lemma})<EOL><DEDENT>return sorted([Lemma(self, lemma_dict) for lemma_dict in lemma_dicts])<EOL>
Looks up lemmas in the GermaNet database.

Arguments:
- `lemma`:
- `pos`: