code: def complete_io(self, iocb, msg):
          
          if _debug: IOController._debug("complete_io %r %r", iocb, msg)
  
          # if it completed, leave it alone
          if iocb.ioState == COMPLETED:
              pass
  
          # if it already aborted, leave it alone
          elif iocb.ioState == ABORTED:
              pass
  
          else:
              # change the state
              iocb.ioState = COMPLETED
              iocb.ioResponse = msg
  
              # notify the client
              iocb.trigger()
docs: Called by a handler to return data to the client.