docs: def _add_list_getter(self):
          """
          Add a read-only ``{prop_name}_lst`` property to the element class to
          retrieve a list of child elements matching this type.
          """
          prop_name = '%s_lst' % self._prop_name
          property_ = property(self._list_getter, None, None)
          setattr(self._element_cls, prop_name, property_)