shoutbox.module

<?php

function shoutbox_theme($existing, $type, $theme, $path) {
  $themes['shoutbox'] = [
    'render element' => 'elements',
    'file' => 'shoutbox.page.inc',
    'template' => 'shoutbox',
  ];
  $themes['shout'] = [
    'render element' => 'elements',
    'file' => 'shout.page.inc',
    'template' => 'shout',
  ];
  return $themes;
}