Octocat，看着喜欢就都下载下来了

HttpClient client = new HttpClient();
var htmlSource = new JumonyParser().LoadDocument("https://octodex.github.com/").Find("a.preview-image > img");
Parallel.ForEach(htmlSource, async htmlElement =>
{
    var src = string.Format(@"https://octodex.github.com{0}", htmlElement.Attribute("data-src").Value());
    var filename = string.Format(@"F:\octocat\{0}", src.Substring(src.LastIndexOf(‘/‘) + 1));
    using (var stream = await client.GetStreamAsync(src))
    {
        using (var fileStream = new FileStream(filename, FileMode.CreateNew))
        {
            byte[] buffer = new byte[8192];
            int byteRead = -1;
            while ((byteRead = stream.Read(buffer, 0, 8192)) > 0)
            {
                fileStream.Write(buffer, 0, byteRead);
            }
        }
    }
    Console.WriteLine(filename);
});
Console.WriteLine("done!");