goToSlide(index = false) {
        this.prevActiveSlide = this.activeSlide;
        this.prevActiveSlideIndex = this.index;

        if (!this.loop() && (index < 0 || index > this.elements.length - 1)) {
            return false;
        }
        if (index < 0) {
            index = this.elements.length - 1;
        } else if (index >= this.elements.length) {
            index = 0;
        }
        this.showSlide(index);
    }
Go to sldei
calls set slide
@param {Int} - index