WP Editor Add Body Class

//Editor Add class
function cms_custom_editor_body_class($mce_init) {
    if (isset($mce_init['body_class'])) {
        $mce_init['body_class'] .= ' editor_'.CMS_KEY_PREFIX;
    } else {
        $mce_init['body_class'] = ' editor_'.CMS_KEY_PREFIX;
    }
    return $mce_init;
}
add_filter('tiny_mce_before_init', 'cms_custom_editor_body_class');