-- deltatime.get([<unit>]) - For getting deltatime. (returns float number)
If unit param is nothing, returns seconds.
If unit param is something like seconds / minutes / hours, it will returns seconds(same as nothing) / minutes / hours.

-- deltatime.add(<sec>, <min>, <hour>) - For adding a time to deltatime.
If you just want to add 15 seconds, it must to be something like that: deltatime.add(15, 0, 0)

Thanks for using this mod!