code: function scale(x, y) {
           return this._set(this._x * x, this._y * (typeof y !== "undefined" ? y : x));
         }
docs: Multiply this vector values by the given scalar
  @name scale
  @memberOf me.ObservableVector2d
  @function
  @param {Number} x
  @param {Number} [y=x]
  @return {me.ObservableVector2d} Reference to this object for method chaining