mediawiki-extensions-ConfirmEdit/includes/specials/SpecialCaptcha.php

<?php
class CaptchaSpecialPage extends UnlistedSpecialPage {
	public function __construct() {
		parent::__construct( 'Captcha' );
	}

	function execute( $par ) {
		$this->setHeaders();

		$instance = ConfirmEditHooks::getInstance();

		switch( $par ) {
			case "image":
				if ( method_exists( $instance, 'showImage' ) ) {
					return $instance->showImage();
				}
			case "help":
			default:
				return $instance->showHelp();
		}
	}
}