code: def on_service_arrival(self, svc_ref):
          
          with self._lock:
              if svc_ref not in self.services:
                  # Get the new service
                  service = self._context.get_service(svc_ref)
  
                  if self._future_value is None:
                      # First value
                      self._future_value = []
  
                  # Store the information
                  self._future_value.append(service)
                  self.services[svc_ref] = service
  
                  self._ipopo_instance.bind(self, service, svc_ref)
                  return True
  
              return None
docs: Called when a service has been registered in the framework
  
          :param svc_ref: A service reference