Function change_time 

pub(crate) fn change_time(
    qt: &CxxQtThread<Sioul>,
    shared: &Arc<Shared>,
    key: &str,
    edit: &str,
) -> String

Any stretch of time changed once noted, by the timer or by hand: its start, its end, what it was, its task, its project. Billed time stays as billed. Returns what went wrong, else “”.