code: def score(self, weight_in_top, weight_in_collection, top_total):
      raise NotImplementedError
  
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 3 for calling the ExpansionModel obj's underlying member method code with example usage: obj.score(weight_in_top, weight_in_collection, top_total) without return types