Discrete timer for simulations.
npm install sim-timer
Singleton constructor for Timer.
Returns either new instance or existing instance of Timer.
Advance time by 1 unit, and call appropriate intervals.
Returns the new time.
delay time delay between calls.
callback function to be called at appropriate tick.
id of the interval. This is used the clear the interval.
Removes the interval from the timer.
id of the interval
Timer for chaining.