PHP5.5 SplQueue

<?php
// FIFO
$queue = new SplQueue();
echo"Enqueuen";
$queue->enqueue('A');
$queue->enqueue('B');
$queue->enqueue('C');
$queue->push('D');
$queue[] = 'E';
foreach($queue as $val) {
echo $val."n";
}
echo"Dequeuen";
$queue->dequeue();
foreach($queue as $val) {
echo $val."n";
}
?>