问Cosine评分在whoosh，python

EN

from whoosh.scoring import Cosine

File "TFIDF.py", line 4, in <module>
    from whoosh.scoring import Cosine
ImportError: cannot import name Cosine

import whoosh
from whoosh.scoring import Cosine
from whoosh.fields import *
from whoosh.scoring import *
from whoosh.qparser import *
from whoosh.query import *
from whoosh.index import open_dir

#Index path
lab3dir= "../lab3/Aula3_1/"
ix = open_dir(lab3dir + "indexdir") #Index generated in previous lab


def cosine(queryTerms):
    list=[]
    dict={} # dict com ID do doc e Similiaridade 
    with ix.searcher(weighting=whoosh.scoring.Cosine()) as searcher:
        query = QueryParser("content", ix.schema, group=OrGroup).parse(u(queryTerms))
        results = searcher.search(query, limit=100)
        for i,r in enumerate(results):
            list.append(r["id"])
            print r, results.score(i)
            dict[r["id"]]= results.score(i)
    return dict