class_docstr: Bleu scorer.
class_docstr_tok: ["Bleu","scorer","."]
docstr: copy the refs.
docstr_tok: ["copy","the","refs","."]
code: def copy(self):
      """copy the refs."""
      new = BleuScorer(n=self.n)
      new.ctest = copy.copy(self.ctest)
      new.crefs = copy.copy(self.crefs)
      new._score = None
      return new
  
imports: import copy
  import math
  from builtins import dict, range
  from collections import defaultdict
label_desc: Use image node_id 1 for calling the BleuScorer obj's underlying member method code with example usage: obj.copy() and returns: new