Flask decorator question.

[Hubert51]

I have two upload zone in one html page. So I am not sure how to let code to know whether zone is used by user to upload file. Now it can work correctly, I have two routes and two functions to handle the upload file.
The first route is @app.route('/upload_sheet', methods=['POST', 'GET'])
The first function is def upload_sheet():
The second route is @app.route('/', methods=['POST', 'GET']).
The second function is def upload_answer():
And in my html file, the first action is action_view='upload_answer' .
The second action is action_view='upload_sheet'
I want to know how this work