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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 create_rich_menu(self, rich_menu, timeout=None):
 """Call create rich menu API. https://developers.line.me/en/docs/messaging-api/reference/#create-rich-menu :param rich_menu: Inquired to create a rich menu object. :type rich_menu: T <= :py:class:`linebot.models.rich_menu.RichMenu` :param timeout: (optional) How long to wait for the server to send data before giving up, as a float, or a (connect timeout, read timeout) float tuple. Default is self.http_client.timeout :type timeout: float | tuple(float, float) :rtype: str :return: rich menu id """

        response = self._post(
            '/v2/bot/richmenu', data=rich_menu.as_json_string(), timeout=timeout
        )

        return response.json.get('richMenuId')