function Scheduler(SchedulerAction, now) {
        if (now === void 0) { now = Scheduler.now; }
        this.SchedulerAction = SchedulerAction;
        this.now = now;
    }
An execution context and a data structure to order tasks and schedule their
execution. Provides a notion of (potentially virtual) time, through the
`now()` getter method.

Each unit of work in a Scheduler is called an {@link Action}.

```ts
class Scheduler {
  now(): number;
  schedule(work, delay?, state?): Subscription;
}
```

@class Scheduler