code: def score(self, weight_in_top, weight_in_collection, top_total):
      f = weight_in_collection / self.N
      return weight_in_top * log((1.0 + f) / f, 2) + log(1.0 + f, 2)
  
imports: from __future__ import division
  import random
  from collections import defaultdict
  from math import log
  from whoosh.compat import xrange, iteritems
label_desc: Use image node_id 2 for calling the Bo1Model obj's underlying member method code with example usage: obj.score(weight_in_top, weight_in_collection, top_total) and returns: unknown