code: def _percent_match(date_classes, tokens):
      
      match_count = [0] * len(date_classes)
  
      for i, date_class in enumerate(date_classes):
          for token in tokens:
              if date_class.is_match(token):
                  match_count[i] += 1
  
      percentages = tuple([float(m) / len(tokens) for m in match_count])
      return percentages
docs: For each date class, return the percentage of tokens that the class matched (floating point [0.0 - 1.0]). The
      returned value is a tuple of length patterns. Tokens should be a list.