code: def compute_group_count(self, pattern):
          
          group_count = self.group_count
          pattern_repeated = 1
          if self.is_many():
              pattern_repeated = 2
          return group_count + pattern_repeated * pattern_group_count(pattern)
docs: Compute the number of regexp match groups when the pattern is provided
          to the :func:`Cardinality.make_pattern()` method.
  
          :param pattern: Item regexp pattern (as string).
          :return: Number of regexp match groups in the cardinality pattern.