docs: def build(self, builder):
          """Build XML by appending to builder"""
          params = dict()
          builder.start(self.__class__.__name__, params)
          for street in self.street_names:
              street.build(builder)
          # build the children
          for child in ('city', 'country', 'state_prov', 'postal_code', 'other_text'):
              if getattr(self, child) is not None:
                  getattr(self, child).build(builder)
          builder.end(self.__class__.__name__)