safe echo of query string

<html>

<head>
    <title>Safe Echoing of Query String Parameters</title>
</head>
<body>
    City: <?php safe_echo('city', 'your hometown') ?>
</body>
</html>
<?php
/**
 * Paste me at the bottom of your page or make a file and require_once()
 *
 * <?php safe_echo('city', 'Your Town'); ?>
 *
 * @param $param
 * @param string $default
 */
function safe_echo($param, $default = '')
{
    $value = $default;

    if (!empty($_REQUEST[$param]))
        $value = htmlspecialchars($_REQUEST[$param]);

    echo $value;
}
?>