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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def stop(self) -> None: """Stops listening for new connections. Requests currently in progress may still continue after the server is stopped. """

        if self._stopped:
            return
        self._stopped = True
        for fd, sock in self._sockets.items():
            assert sock.fileno() == fd
            # Unregister socket from IOLoop
            self._handlers.pop(fd)()
            sock.close()