class_docstr: Bleu scorer.
class_docstr_tok: ["Bleu","scorer","."]
code: def ratio(self, option=None):
      self.compute_score(option=option)
      return self._ratio
  
imports: import copy
  import math
  from builtins import dict, range
  from collections import defaultdict
label_desc: Use image node_id 4 for calling the BleuScorer obj's underlying member method code with example usage: obj.ratio(option) and returns: self