public async Task <string> DeleteAsync(string url, object requestParams = null, Dictionary <string, string> headers = null)
        {
            var response = await HttpRequestHelper.Delete(url, requestParams, headers);

            return(await ContentToString(response));
        }
        public async Task <string> PutAsync(string url, object data = null, Dictionary <string, string> headers = null, Encoding coding = null)
        {
            var response = await HttpRequestHelper.Put(url, data, headers, coding);

            return(await ContentToString(response));
        }