code: def group(self):
          
          lowerbound = self.lowerbound
          age_group_list = []
          for age_group in self.et.findall("group"):
              upperbound = age_group.attrib["upperbound"]
              try:
                  poppercent = age_group.attrib["poppercent"]
              except KeyError:
                  poppercent = None
              age_group_list.append({"lowerbound": lowerbound,
                                     "upperbound": upperbound,
                                     "poppercent": poppercent})
              lowerbound = upperbound
          return age_group_list
docs: :rtype: list