If you were modifying the admin bar in WordPress 3.x you used to call this:
// Add a link to the dashboard in the [pre-existing] site-name node $wp_admin_bar->add_menu( array( 'parent' => 'site-name', 'id' => 'dashboard', 'title' => 'Dashboard', 'href' => admin_url(), ) );
to add a new item to your admin toolbar. Now you just replace
add_node – they have exactly the same effect – and exactly the same syntax – just a slightly different semantic effect on the reader.