class_docstr: Bleu scorer.
class_docstr_tok: ["Bleu","scorer","."]
docstr: add an instance (e.g., from another sentence).
docstr_tok: ["add","an","instance","(","e.g.",",","from","another","sentence",")","."]
code: def __iadd__(self, other):
      """add an instance (e.g., from another sentence)."""
  
      if type(other) is tuple:
          # avoid creating new BleuScorer instances
          self.cook_append(other[0], other[1])
      else:
          assert self.compatible(other), "incompatible BLEUs."
          self.ctest.extend(other.ctest)
          self.crefs.extend(other.crefs)
          self._score = None  # need to recompute
  
      return self
  
imports: import copy
  import math
  from builtins import dict, range
  from collections import defaultdict
label_desc: Use image node_id 12 for calling the BleuScorer obj's underlying member method code with example usage: obj.__iadd__(other) and returns: self