code: def on_service_arrival(self, svc_ref):
          
          with self._lock:
              if self._value is None:
                  # Inject the service
                  self.reference = svc_ref
                  self._value = self._context.get_service(svc_ref)
  
                  self._ipopo_instance.bind(self, self._value, self.reference)
                  return True
  
          return None
docs: Called when a service has been registered in the framework
  
          :param svc_ref: A service reference