class_docstr: A constraint that prevents modifying words beyond certain percentage of
  total number of words.
  
  Args:
      max_rate (:obj:`float`):
          Percentage of words that can be modified. For example, given text of 20 words, `max_rate=0.1` will allow at most 2 words to be modified.
      min_threshold (:obj:`int`, optional, defaults to :obj:`1`):
          The minimum number of words that can be perturbed regardless of `max_rate`. For example, given text of 20 words and `max_rate=0.1`,
          setting`min_threshold=4` will still allow 4 words to be modified even though `max_rate=0.1` only allows 2 words. This is useful since
          text length can vary a lot between samples, and a `N%` modification limit might not make sense for very short text.
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code: def extra_repr_keys(self):
      return ["max_rate", "min_threshold"]
  
imports: import math
  from textattack.constraints import PreTransformationConstraint
label_desc: Use image node_id 3 for calling the MaxModificationRate obj's underlying member method code with example usage: obj.extra_repr_keys() and returns: list