if ($categories = get_categories()) {

                                                $exclude = mfn_get_excluded_categories();

                                                foreach ($categories as $category) {

                                                    $class = false;

                                                    if ($exclude && in_array($category->slug, $exclude)) {
                                                        continue;
                                                    }
                                                    if( is_category() && $current_id == $category->term_id ){
                                                        $class = 'current-cat';
                                                    }

                                                    echo '<li class="'. esc_attr($class) .'"><a data-rel=".category-'. esc_attr($category->slug) .'" href="'. esc_url(get_term_link($category)) .'">'. esc_html($category->name) .'</a></li>';

                                                }
                                            }