current Yahoo userid status in php

The given PHP example returns the current Yahoo status(online/offline) against a yahoo userid.

<?php

function yahoo($id){

$url = 'http://opi.yahoo.com/online?u=';

$data = file_get_contents($url . $id);

if (trim(strtolower(strip_tags($data))) != 'user not specified.') {

return (strlen($data) == 140) ? 'online' : 'offline';

} else {

return trim(strip_tags($data));

}

}

echo yahoo("yahoo_userid");

?>