Wordpress如何调用搜索框

/**
* Add searchbox in menubar
*/
add_filter( 'wp_nav_menu_items','add_search_box', 10, 2 );
function add_search_box( $items, $args ) {
$items .= '
<ul>
<li>&#39; . get_search_form( false ) . &#39;</li>
</ul>
&#39;;
return $items;
}

.searchbox-position {
margin-top: 15px;
margin-right: 20px;
}