Function timingSourceFactory

timingSourceFactory(
    source: TimingSources,
    duration: number,
    options?: Partial<ModSettableOptions>,
): TimingSourceFactory
A factory function for creating a timing source. It returns a function which creates a designated timer.

This is useful in times where you need to recreate timers, eg for reset type of behaviours because the options for the timer to be consolidated in one place.
```
// Get a factory for an elapsed timer
const factory = sources(`elapsed`, 1000);

// Create the timer
let t = factory();

// Get a value from the timer
const value = t();

// Recreate the timer, note we don't need any options
t = factory();
```
Parameters
- source: TimingSources
  Kind of timer to make
- duration: number
  Duration depends on the timer used. Will be milliseconds, hertz or bpm.
- options: Partial<ModSettableOptions> = {}
  Options to pass to timer.
Returns TimingSourceFactory