public async Task <string> Upload(Uri uri)
{
string guid = GuidHelper.Gen().ToString();
AsyncHttpClient asyncHttpClient = new AsyncHttpClient();
var result = await asyncHttpClient.DefaultUserAgent().Referer(uri.AbsoluteUri).Uri(uri).Get();
string fileExtension = "png";
return(await Upload(guid.ToString() + "." + fileExtension, result.GetBytes()));
}