function Scale(a, b, life, easing) {
      var _this;
      _this = _Behaviour.call(this, life, easing) || this;
      _this.same = void 0;
      _this.name = void 0;
      _this.reset(a, b);
      _this.name = "Scale";
      return _this;
    }
Creates a new Scale instance.
@param {number|Span} [a=1] - The initial scale value or range.
@param {number|Span} [b] - The final scale value or range. If not provided, it will be the same as 'a'.
@param {number} [life=Infinity] - This behaviour's life.
@param {string} [easing='easeLinear'] - This behaviour's easing function.