gistfile1.php

<?php
$header_menu_query = get_transient( 'header_menu_query' );
if( $header_menu_query === false ) {
	if ( has_nav_menu( 'header-menu' ) ) {
		$header_menu_query = wp_nav_menu( array(
			'menu'   			=> '33',
			'depth'      		=> 3,
			'container'  		=> 'nav',
			'menu_class' 		=> 'nav nav-pills',
			'fallback_cb' 		=> 'wp_page_menu',
			'walker' 			=> new wp_bootstrap_navwalker(),
			'echo'				=> 0,
		) );
	}
	set_transient( 'header_menu_query', $header_menu_query, 60*60*24 );
}
echo $header_menu_query;