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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 close(self):
 """Stops accepting new connections, cancels all currently running requests. Request handlers are able to handle `CancelledError` and exit properly. """

        if self._server is None:
            raise RuntimeError('Server is not started')
        self._server.close()
        for handler in self._handlers:
            handler.close()