Creates a timer and binds a callback predicate to it.
timer_create/2 creates a timer and binds the callback predicate
Callback to it. The timer object will be unified with Timer.
A timer has to be deleted with timer_close/1.
If Callback is 'null' than no callback predicate will be
bound to the timer. This may be useful, if you want to check
explicitly the state of the timer (running or elapsed) with the predicate
timer_is_active/1. If Callback is a compound term
and its first argument is a variable, then the callback predicate will
be called with the Timer as it's first argument.
Callback predicate (compound or atom) Timer timer
This predicate is not part of the ISO-Prolog Standard.