code: def schedule_servicegroup_host_downtime(self, servicegroup, start_time, end_time,
                                              fixed, trigger_id, duration, author, comment):
          
          for host in [s.host for s in servicegroup.get_services()]:
              self.schedule_host_downtime(host, start_time, end_time, fixed,
                                          trigger_id, duration, author, comment)
docs: Schedule a host downtime for each host of services in a servicegroup
          Format of the line that triggers function call::
  
          SCHEDULE_SERVICEGROUP_HOST_DOWNTIME;<servicegroup_name>;<start_time>;<end_time>;<fixed>;
          <trigger_id>;<duration>;<author>;<comment>
  
          :param servicegroup: servicegroup to schedule downtime
          :type servicegroup: alignak.object.servicegroup.Servicegroup
          :param start_time: downtime start time
          :type start_time:
          :param end_time: downtime end time
          :type end_time:
          :param fixed: is downtime fixed
          :type fixed: bool
          :param trigger_id: downtime id that triggered this one
          :type trigger_id: str
          :param duration: downtime duration
          :type duration: int
          :param author: downtime author
          :type author: str
          :param comment: downtime comment
          :type comment: str
          :return: None