Site location request follows:
http://www.ahfu.com/ahfuzhang/?__debugger__=yes&cmd=resource&f=style.css
actually the normal range of the content of the CSS file, but the code does not deal with the site's path, nor this file.
So this is the flask back door.
if name == 'main':
app.debug = False
If you turn off the debug option just fine.