jQuery.fn.slide = function(next, interval, img_total, img_visible){
	var step = 0;
	//total = interval*(img_total/2);
	total = interval*(img_total-img_visible);
	//alert(total);
	$(next).click(function(){
		//alert(step);
		step+=interval;
		effect = "fast";
		if(step>=total) step = 0;
		$('.line_items').hide();
		$('.line_items').css("left", "-"+step+"px").fadeIn("slow");
		//alert(step);
	});	
 };