class_docstr: Bleu scorer.
class_docstr_tok: ["Bleu","scorer","."]
code: def retest(self, new_test):
      if type(new_test) is str:
          new_test = [new_test]
      assert len(new_test) == len(self.crefs), new_test
      self.ctest = []
      for t, rs in zip(new_test, self.crefs):
          self.ctest.append(cook_test(t, rs))
      self._score = None
  
      return self
  
imports: import copy
  import math
  from builtins import dict, range
  from collections import defaultdict
label_desc: Use image node_id 9 for calling the BleuScorer obj's underlying member method code with example usage: obj.retest(new_test) and returns: self