Function fire_due_timers 

pub fn fire_due_timers<H: ScriptHost + Resource<Mutability = Mutable>>(
    host: ResMut<'_, H>,
    due: Res<'_, DueTimers>,
    out: MessageWriter<'_, ScriptCommandEvent>,
)

Fire on_timer(name) for every timer retire_due_timers collected this tick. A host that defines no matching handler ignores the call, so in an app running several languages the timer reaches whichever host declared it.