OOP Learning Mode

Assume that the Pluto and Grumpy classes are both declared in the class. definitions.php file, which is in the same directory as this script. What will happen when you run this script?

<?php
$a = function() {
include('class.definitions.php');
};
spl_autoload_register($a);
// Class Pluto is defined in class.definitions.php
$planet = new Pluto;
// Class Grumpy is defined in class.definitions.php
$dwarf = new Grumpy;