code: function normalizeTweenValues(tween, animatable) {
    const t = {};
    for (let p in tween) {
      let value = getFunctionValue(tween[p], animatable);
      if (is.arr(value)) {
        value = value.map(v => getFunctionValue(v, animatable));
        if (value.length === 1) value = value[0];
      }
      t[p] = value;
    }
    t.duration = parseFloat(t.duration);
    t.delay = parseFloat(t.delay);
    return t;
  }
docs: Tweens