Function take 

pub fn take(
    engine: &Engine,
    profile: &Profile,
    sign_in: &SignIn,
) -> Result<usize, Problem>

Takes the login out of the window’s home and stores it with the profile, and answers how many files it stored.

It is taken by a short-lived container of its own that mounts the same home, rather than from the window’s: the window may be closed already, and a closed container cannot be run in. The storing itself is the one every harness’s login goes through.

Errors

Problem::NoLogin when the home holds no whole login, or the engine’s words when it refuses.