How can I create a custom post type with its own taxonomy?

<!-- BEGIN COPY / PASTE -->
    function my_custom_post_type() {
        $args = array(
            'public' => true,
            'label'  => 'Books',
            'supports' => array('title', 'editor', 'thumbnail'),
        );
        register_post_type('book', $args);
    }
    add_action('init', 'my_custom_post_type');

    function my_custom_taxonomy() {
        $args = array(
            'label' => 'Genres',
            'rewrite' => array('slug' => 'genre'),
            'hierarchical' => true,
        );
        register_taxonomy('genre', 'book', $args);
    }
    add_action('init', 'my_custom_taxonomy');
    <!-- END COPY / PASTE -->