Function linux_session 

fn linux_session(answers: &LinuxAnswers, now: Duration) -> Session

The session as a Linux or BSD desktop’s answers say it, now the real clock since the epoch: locked when a locker says so and none says otherwise, disputed when they disagree (logind’s hint left locked by a locker that died, while the desktop’s own screen saver says unlocked); the shortest time since input any of them gave.