how to get variable $handler inside the function

<?php
require '../settings.php';

class Db {

    protected static $instance = null;

public static function getInstance()
{
if (is_null(self::$instance)) {
self::$instance = new self();
}

return self::$instance;
}


}

// Tada galime naudoti

try
{
     $handler = new PDO('mysql:host=localhost;dbname=mistic_rpe', login, password);
    $handler ->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}catch (PDOException $e) {
echo "pagavo";
}
//$result = Db::getInstance()->query($sql);
/*
function execute($sql){

$result = mysql_query($sql);
    return true;
if (!$result) {
    return false;
}



}

execute('CREATE DATABASE my_db;');
*/

function execute($sql)
{

    $query = $handler->query('SELECT * FROM Bandymas');
    while ($r = $query->fetch()) {
        echo $r['name'], "<br>";
    }
};