class_docstr: A constraint on edit distance (Levenshtein Distance).
  We use the Levenshtein Distance div the long of the sentence as score.
  
  :param ~textflint.input.dataset origin_dataset:
          the dataset of origin sample
  :param ~textflint.input.dataset trans_dataset:
      the dataset of translate sample
  :param str|list fields: the name of the origin field need compare.
code: def __repr__(self):
      return "EditDistance"
  
imports: import editdistance
  from .validator import Validator
label_desc: Use image node_id 2 for calling the EditDistance obj's underlying member method code with example usage: obj.__repr__() and returns: str