const Clock = rxify((initialProps, prop$) => {
  return prop$
    .pipe(
      filter(pd => pd.differences.includes('running')),
      map(pd => pd.next.running),
      switchMap(running => running ? interval(0, 1000) : empty()),
      startWith(1),
      map(_ => (<span className="time">{new Date().toLocaleTimeString()}</span>))
    )
});