const request = (params, opts, success, fail, complete) => {   params = formatParams(params)   params.Action = firstLetterUpper(params.Action)   var defaultParams = _buildParams()   params = Object.assign(defaultParams, params)   var method = (opts.method || 'GET').toUpperCase()   var normalized = normalize(params)   var canonicalized = canonicalize(normalized)   var stringToSign = `${method}&${encode('/')}&${encode(canonicalized)}`   const key = 'u92uXpgg0jOuRf3wtd41Df1kxfqwAG' + '&'   var signature = crypto.HMAC(crypto.SHA1, stringToSign, key, {     asBase64: true   })   normalized.push(['Signature', encode(signature)])   const url = method === 'POST' ? `${'https://iot.cn-shanghai.aliyuncs.com'}/` : `${'https://iot.cn-shanghai.aliyuncs.com'}/?${canonicalize(normalized)}`   if (method === 'POST') {     opts.headers = opts.headers || {};     opts.headers['content-type'] = 'application/x-www-form-urlencoded'     opts.data = canonicalize(normalized)   }   wx.request({     url: url,     data: opts.data ? opts.data : {},     header: opts.headers,     method: method,     dataType: 'json',     responseType: 'text',     success: function(res) {       if (typeof success === 'function')         success(res)       else         console.log("success is not a function")     },     fail: function(res) {       if (typeof fail === 'function')         fail(res)       else         console.log("fail is not a function")     },     complete: function(res) {       if (typeof complete === 'function')         complete()       else         console.log("complete is not a function")     }   }) } 以上代码在云函数运行，提示wx is not defined，有没有朋友能帮我把这段代码该成在云函数里可以用的。 多谢！