Flask-login and LDAP

I'm developing a webapp with the flask framework as a backend and I need to provide authentication. Since this is an in-house app to be used on our local domain I have chosen to authenticate user with their already present domain credentials. The method I use is the `win32security.LogonUser` from `pywin32` which returns a handle on successful login. I have tried to understand how flask-login works, but the `@login_manager.user_loader` callback makes me confused. It says I should provide an id which can be used to reload the user, however I have no database or persistent storage to provide this mapping from, since I'm only interesting in checking if the user pass authentication. My User class looks like this: ``` class User(flask_login.UserMixin): def __init__(self,username): self.username = username self.id = ??? ``` What to use an `id`, and how could this id map back to this instance?