code: def check_exclude_rec(self):
          # pylint: disable=access-member-before-definition
          
          if self.rec_tag:
              msg = "[timeentry::%s] is in a loop in exclude parameter" % (self.get_name())
              self.add_error(msg)
              return False
          self.rec_tag = True
          for timeperiod in self.exclude:
              timeperiod.check_exclude_rec()
          return True
docs: Check if this timeperiod is tagged
  
          :return: if tagged return false, if not true
          :rtype: bool