code: def find_srv_by_name_and_hostname(self, host_name, sdescr):
          
          key = (host_name, sdescr)
          return self.name_to_item.get(key, None)
docs: Get a specific service based on a host_name and service_description
  
          :param host_name: host name linked to needed service
          :type host_name: str
          :param sdescr:  service name we need
          :type sdescr: str
          :return: the service found or None
          :rtype: alignak.objects.service.Service