code: function moveToPrevious(priv) {
    moveTo(priv, (priv.toIndex - 1 + priv.slides.length) % priv.slides.length);
  }
docs: Moves slider previous slide.
  
  @precondition ${link Slider.prototype.start} was called on this slider
  
  @fqn Slider.prototype.moveToPrevious