where should i define filter functions for router?

hi, i try to learn about rountig
everything is ok but have only one problem

where should i define the filter functions filterInFunc and filterOutFunc

<?php

$route = new Route('<presenter>/<action>/<id>', [
	'presenter' => [
		Route::VALUE => 'Homepage',
		Route::FILTER_IN => 'filterInFunc',
		Route::FILTER_OUT => 'filterOutFunc',
	],
	'action' => 'default',
	'id' => null,
]);

?>

thank you !