header_register_callback

<?

header('Content-Type: text/plain');
header('X-Test: test');

function test() {
 foreach (headers_list() as $header) {
   if (strpos($header, 'X-Powered-By:') !== false) {
     header_remove('X-Powered-By');
   }
   header_remove('X-Test');
 }
}

$result = header_register_callback(test());

print_r(headers_list());
echo "a";

?>