Get the hook suffix without an object or class

pseudo-encapsulation.php

<?php

namespace JPB\Some_Plugin;

function get_hook_suffix() {
	return apply_filters( 'jpb.some_plugin.get_hook_suffix', '' );
}

function register_page() {
	$hook_suffix = add_submenu_page( /* Arguments */ );
	add_filter( 'jpb.some_plugin.get_hook_suffix', function() use ( $hook_suffix ) {
		return $hook_suffix;
	} );
}

add_filter( 'admin_menu', '\JPB\Some_Plugin\register_page' );