How to use the ember-animated.clock.now function in ember-animated

import { clock, rAF } from 'ember-animated';

let origNow = clock.now;

export default class TimeControl {
  constructor() {
    if (clock.now !== origNow) {
      throw new Error("Only one TimeControl may be active at a time");
    }
    this._timer = origNow();
    this._runningSpeed = false;
    this._runStartedAt = null;
    clock.now = () => this.now();
  }
  finished() {
    clock.now = origNow;
  }
  now() {
    if (this._runningSpeed) {

constructor() {
    if (clock.now !== origNow) {
      throw new Error("Only one TimeControl may be active at a time");
    }
    this._timer = origNow();
    this._runningSpeed = false;
    this._runStartedAt = null;
    clock.now = () => this.now();
  }
  finished() {

constructor() {
    if (clock.now !== origNow) {
      throw new Error("Only one TimeControl may be active at a time");
    }
    this._timer = origNow();
    this._runningSpeed = false;
    this._runStartedAt = null;
    clock.now = () => this.now();
  }
  finished() {