code: def _parse_group(self, element):
          
          self._log.debug('Adding Trigger group: {group}'.format(group=element.text))
          if isinstance(self.groups, set):
              self.groups.add(element.text)
          elif self.groups is None:
              self.groups = {element.text}
          else:
              raise TypeError('Unrecognized group type, {type}: {groups}'
                              .format(type=type(self.groups), groups=str(self.groups)))
docs: Parse and add a group requirement for this trigger
          :param element: The XML Element object
          :type  element: etree._Element