previous_selected_photo = "";
function change_product_photo(arg_photo_number) {
	var src_part, ext, href;
	
	//HIDE all previously open spans (if they exist)
	if (document.getElementById("alternate_product_photo_" + previous_selected_photo)) {
		document.getElementById("alternate_product_photo_" + previous_selected_photo).border = "1";
	}
	
	//SHOW the selected SPAN tag + GROUP BY span tag (if they exist)
	if (document.getElementById("alternate_product_photo_" + arg_photo_number)) {
		document.getElementById("alternate_product_photo_" + arg_photo_number).border = "2";
		ext = document.getElementById("alternate_product_photo_" + arg_photo_number).src;
		
		document.getElementById("product_photo").src = ext;
	}
	//SAVE the previous span to global variable for next call of this function
	previous_selected_photo = arg_photo_number
}