def get_qrcode(self):
return self._get('<STR_LIT>')<EOL>
获取体验小程序的体验二维码
返回 Response 类型，header 中带有 Content-Type 与 Content-disposition 类型
详情请参考
https://open.weixin.qq.com/cgi-bin/showdocument?action=dir_list&id=open1489140610_Uavc4

:rtype: requests.Response