SplHeapTop ordered Heap

Code
<?php

$heap 
= new SplMaxHeap();
$heap->insert('c');
$heap->insert('b');
$heap->insert('a');
$heap->insert('d');

echo 
'top element: ' $heap->top() . PHP_EOL;

foreach(
$heap as $val) {
    echo 
$val PHP_EOL;
}
Result
top element: d
d
c
b
a
Used Versions
PHP 7.2, Zend 3.0, Symfony 4.0, Laravel 5.6, PHPUnit 6.5, Doctrine 2.8