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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 logout(self, auth_secret):
 """Log out of a user. Parameters auth_secret: str The authentication secret of the logged-in user. Returns ------- bool True if the logout is successful, False otherwise. result None if the logout is successful, a dict containing the error string with the key ERROR_KEY otherwise. Note ---- Possible error strings are listed as below: - ERROR_NOT_LOGGED_IN """

        result = {pytwis_constants.ERROR_KEY: None}

        # Check if the user is logged in.
        loggedin, userid = self._is_loggedin(auth_secret)
        if not loggedin:
            result[pytwis_constants.ERROR_KEY] = pytwis_constants.ERROR_NOT_LOGGED_IN
            return (False, result)

        # Generate the new authentication secret.
        new_auth_secret = secrets.token_hex()

        # Replace the old authentication secret by the new one.
        userid_profile_key = pytwis_constants.USER_PROFILE_KEY_FORMAT.format(userid)
        with self._rc.pipeline() as pipe:
            pipe.multi()
            pipe.hset(userid_profile_key, pytwis_constants.AUTH_KEY, new_auth_secret)
            pipe.hset(pytwis_constants.AUTHS_KEY, new_auth_secret, userid)
            pipe.hdel(pytwis_constants.AUTHS_KEY, auth_secret)
            pipe.execute()

        result[pytwis_constants.USERNAME_KEY] = \
            self._rc.hget(userid_profile_key, pytwis_constants.USERNAME_KEY)
        result[pytwis_constants.AUTH_KEY] = ''
        return (True, result)