function showobj(x) {if(x != null && x.className == "hidden") x.className = "shown";}
function hideobj(x) {if(x != null && x.className == "shown") x.className = "hidden";}
function flipobj(x) {if(x != null && x.className == "shown") x.className = "hidden"; else if(x != null && x.className == "hidden") x.className = "shown";}
function show(name) {showobj(document.getElementById(name));}
function hide(name) {hideobj(document.getElementById(name));}
function flip(name) {flipobj(document.getElementById(name));}