class_docstr: A constraint representing a maximum allowed perturbed words.
  
  Args:
      max_num_words (:obj:`int`, optional): Maximum number of perturbed words allowed.
      max_percent (:obj: `float`, optional): Maximum percentage of words allowed to be perturbed.
      compare_against_original (bool):  If `True`, compare new `x_adv` against the original `x`.
          Otherwise, compare it against the previous `x_adv`.
class_docstr_tok: ["A","constraint","representing","a","maximum","allowed","perturbed","words",".","Args",":","max_num_words","(",":","obj",":","`","int","`",",","optional",")",":","Maximum","number","of","perturbed","words","allowed",".","max_percent","(",":","obj",":","`","float","`",",","optional",")",":","Maximum","percentage","of","words","allowed","to","be","perturbed",".","compare_against_original","(","bool",")",":","If","`","True","`",",","compare","new","`","x_adv","`","against","the","original","`","x","`",".","Otherwise",",","compare","it","against","the","previous","`","x_adv","`","."]
code: def extra_repr_keys(self):
      metric = []
      if self.max_percent is not None:
          metric.append("max_percent")
      if self.max_num_words is not None:
          metric.append("max_num_words")
      return metric + super().extra_repr_keys()
  
imports: import math
  from textattack.constraints import Constraint
label_desc: Use image node_id 3 for calling the MaxWordsPerturbed obj's underlying member method code with example usage: obj.extra_repr_keys() and returns: unknown