Function pick_countdown_secs 

pub fn pick_countdown_secs(
    target: &str,
    micro: Option<u64>,
    long: Option<u64>,
) -> Option<u64>

Select which countdown the tray should show according to the user’s tray_countdown_target setting. "short" returns the micro timer, "long" returns the long timer, anything else returns whichever is sooner (the default "next" behaviour).