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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 _get_socket(self, sid):
 """Return the socket object for a given session."""

        try:
            s = self.sockets[sid]
        except KeyError:
            raise KeyError('Session not found')
        if s.closed:
            del self.sockets[sid]
            raise KeyError('Session is disconnected')
        return s