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//////////////////////////////////////////////////////////////
///////// ADD SEARCHFORM
//////////////////////////////////////////////////////////////
add_filter('wp_nav_menu_items','add_search_box_to_menu', 10, 2);
function add_search_box_to_menu( $items, $args ) {
    if( $args->theme_location == 'primary' )
        return $items.get_search_form();

    return $items;
}