Turning Lighbox images, into a slideshow

I am creating a website. On this site I am using the same Lightbox script I have used for years. Its simple, loads fast and I have never had complaints. Now, this client want something where you click the image, the larger image pops up in the Lightbox, and you need to be able to cycle left and right.
Discover Bulgaria - Holiday Lettings in Bulgaria
Is there anything I can add to the lightbox script to make this cycle through to the next large image?
You can see the Lightbox script here :- CodePen - A Pen by Studio Team

Issue Solved -


<ul> <li><a href="#" class="lightbox">Photo 1</a></li> <li><a href="#" class="lightbox">Photo 2</a></li> <li><a href="#" class="lightbox">Photo 3</a></li> <li><a href="#" class="lightbox">Photo 4</a></li></ul><div id="menu" style="display:none;"> <a href="#" id="prev">&laquo; Prev</a> <a href="#" id="next">Next &raquo;</a></div>$('.lightbox').click(function(){ $('.lightbox').removeClass("active"); $(this).addClass("active"); $('#menu').show();});$('#next').click(function(){ var img_index = $('.lightbox.active').index('.lightbox')+1; if($('.lightbox:eq('+img_index+')').size()==0) $('.lightbox:first').click(); else $('.lightbox:eq('+img_index+')').click();});$('#pr ev').click(function(){ var img_index = $('.lightbox.active').index('.lightbox')-1; if(img_index<0) $('.lightbox:last').click(); else $('.lightbox:eq('+img_index+')').click();});