Function link 

pub(crate) fn link(
    qt: &CxxQtThread<Sioul>,
    shared: &Arc<Shared>,
    from: &str,
    to: &str,
) -> String

Ties two things, in the one that can hold the link: a task (its list syncs it to your other devices), an event whose calendar can be written, a note’s front matter; else the local file, as a message is never changed. Returns what the line says.