How to use the mobx-utils.now function in mobx-utils

      () => now('frame'),
      this.updateStats,

      () => 2 * Math.PI * now('frame') / 1000,
      t => this.simulateWalk(model, t),

get now() {
    return (now('frame') / 1000) - this.model.startTime
  }

    () => 2 * Math.PI * now('frame') / 1000,
    t => simulateWalk(model, t),

get playTime() {
    const time = this.isPlaying
      ? this.currentTime + (now('frame') - this.playStartedAt)
      : this.currentTime

    return time >= this.endTime ? this.endTime : time
  }

@computed get time() {
		return mobxUtils.now(this.interval);
	}

    disposeOnUnmount(this, reaction(() => this.props.animate && now('frame'), this.update))
  }

    this.props.animate && disposeOnUnmount(this, reaction(() => now('frame'), this.update))
  }

    disposeOnUnmount(this, reaction(() => now('frame'), this.onAnimationFrame))
  }

@computed get elapsedTime() {
        if (this.isRunning) {
            return now(TICK_INTERVAL) - this.startTime;
        } else {
            return 0;
        }
    }