function fetch_object(idname)

{

    var my_obj = document.getElementById(idname);

    return my_obj;

}



function toggle_nav(obj)

{

    for (i = 1; i<= 7; i++  )

    {

        

        var nav_img = fetch_object("nav_" + i);

        var sub_nav = fetch_object("sub_nav_" + i);

        var sub_nav_index =  fetch_object("sub_nav_0");

        sub_nav_index.style.display = "none";

        if (obj == i)

        {

            sub_nav.style.display = "block";



        }

        else

        {

            sub_nav.style.display = "none";

        }

    }

}