Warm-up questions for job seekers.

Whats the difference (if any)?

/* Case 1 */
<?php
header('Content-Type: text/css');
$exit_normally = 0;
register_shutdown_function(function() {
	register_shutdown_function(function() {
		global $exit_normally;
		if (!$exit_normally) {
			echo "/*\n".ob_get_clean()."\n*/\n";
		}
	});
});
/* ...do stuff... */
$exit_normally = 1;
exit;

/* Case 2 */
<?php
header('Content-Type: text/css');
$exit_normally = 0;
register_shutdown_function(function() use($exit_normally) {
	register_shutdown_function(function() use($exit_normally) {
		if (!$exit_normally) {
			echo "/*\n".ob_get_clean()."\n*/\n";
		}
	});
});
/* ...do stuff... */
$exit_normally = 1;
exit;

/* Case 3 */
<?php
header('Content-Type: text/css');
$exit_normally = 0;
register_shutdown_function(function() use(&$exit_normally) {
	register_shutdown_function(function() use($exit_normally) {
		if (!$exit_normally) {
			echo "/*\n".ob_get_clean()."\n*/\n";
		}
	});
});
/* ...do stuff... */
$exit_normally = 1;
exit;

/* Case 4 */
<?php
header('Content-Type: text/css');
$exit_normally = 0;
register_shutdown_function(function() use(&$exit_normally) {
	register_shutdown_function(function() use(&$exit_normally) {
		if (!$exit_normally) {
			echo "/*\n".ob_get_clean()."\n*/\n";
		}
	});
});
/* ...do stuff... */
$exit_normally = 1;
exit;