function blink(){
blink_x = 1
blink_y = 1
ticToc();
} 
function ticToc(){
if(blink_x==1){
blink_x=0;
blink_y++;
document.getElementById("blink").style.visibility='visible';
}else {
blink_x=1;
blink_y++;
document.getElementById("blink").style.visibility='hidden';
}
if (blink_y < 40) {setTimeout('ticToc()', 500);}
}