code: def register_handler(self, target=None):
          
          target = target or 'worker'
          sign_num = self.num
  
          def wrapper(func):
  
              _LOG.debug("Registering '%s' as signal '%s' handler ...", func.__name__, sign_num)
  
              uwsgi.register_signal(sign_num, target, func)
  
              return func
  
          return wrapper
docs: Decorator for a function to be used as a signal handler.
  
          :param str|unicode target: Where this signal will be delivered to. Default: ``worker``.
  
              * ``workers``  - run the signal handler on all the workers
              * ``workerN`` - run the signal handler only on worker N
              * ``worker``/``worker0`` - run the signal handler on the first available worker
              * ``active-workers`` - run the signal handlers on all the active [non-cheaped] workers
  
              * ``mules`` - run the signal handler on all of the mules
              * ``muleN`` - run the signal handler on mule N
              * ``mule``/``mule0`` - run the signal handler on the first available mule
  
              * ``spooler`` - run the signal on the first available spooler
              * ``farmN/farm_XXX``  - run the signal handler in the mule farm N or named XXX
  
              * http://uwsgi.readthedocs.io/en/latest/Signals.html#signals-targets