Function thresholdToggle

🔘 Toggles a new subscription to the mapped Observable, once a threshold of events has been detected.

• Any current Subscription is terminated.
• Use when cancelability is important, like a video player tapped both to start and stop.

Example

```

• const momentary = new Subject();
• const light = momentary.pipe(thresholdToggle(1, () => new Observable(o => {
• console.log('connected: true');
• return () => console.log('connected: false');
• }))).subscribe()
• switch.next(); // connected: true
• switch.next(); // connected: false
• ```