code: def create_mailbox(self, actor, loop):
          '''Override :meth:`.Concurrency.create_mailbox` to create the
          mailbox server.
          '''
          mailbox = TcpServer(mailbox_protocol, loop=loop, name='mailbox')
          # when the mailbox stop, close the event loop too
          mailbox.event('stop').bind(lambda _, **kw: loop.stop())
          mailbox.event('start').bind(
              lambda _, **kw: loop.call_soon(self.hand_shake, actor)
          )
          return mailbof create_mailbox(self, actor, loop):
          '''Override :meth:`.Concurrency.create_mailbox` to create the
          mailbox server.
          '''
          mailbox = TcpServer(mailbox_protocol, loop=loop, name='mailbox')
          # when the mailbox stop, close the event loop too
          mailbox.event('stop').bind(lambda _, **kw: loop.stop())
          mailbox.event('start').bind(
              lambda _, **kw: loop.call_soon(self.hand_shake, actor)
          )
          return mailbox
docs: Override :meth:`.Concurrency.create_mailbox` to create the
          mailbox server.