code: def avg_number_word_perturbed_num(self):
      average_num_words = self.all_num_words.mean()
      average_num_words = round(average_num_words, 2)
      return average_num_words
  
file_path: TextAttack/textattack/metrics/attack_metrics/words_perturbed.py
imports: import numpy
  from textattack.attack_results import FailedAttackResult, SkippedAttackResult
  from textattack.metrics import Metric
label_desc: Use image node_id 3 for calling the WordsPerturbed obj's underlying member method code with example usage: obj.avg_number_word_perturbed_num() and returns: average_num_words