code: def _wake(self):
          
          try:
              self.transmit_side.write(b(' '))
          except OSError:
              e = sys.exc_info()[1]
              if e.args[0] != errno.EBADF:
                  raise
docs: Wake the multiplexer by writing a byte. If Broker is midway through
          teardown, the FD may already be closed, so ignore EBADF.