code: def get_service_reference(self, clazz, ldap_filter=None):
          # type: (Optional[str], Optional[str]) -> Optional[ServiceReference]
          
          result = self.__framework.find_service_references(
              clazz, ldap_filter, True
          )
          try:
              return result[0]
          except TypeError:
              return None
docs: Returns a ServiceReference object for a service that implements and
          was registered under the specified class
  
          :param clazz: The class name with which the service was registered.
          :param ldap_filter: A filter on service properties
          :return: A service reference, None if not found