Return the cooldown left for the trigger

$cooldown logically doesn't make sense.

Because #COOLDOWN will disallow users from using the Trigger for a given time, so there is no chance at all to get a $cooldown value other than 0.

For example, even if $cooldown is used, the Trigger contains $cooldown can only be executed when the actual cooldown time is reached. So when $cooldown is finally executed, its value is already 0 at that point.