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add_theme_support('menus');

register_sidebar(
    array(
        'before_widget' => '<div class="widget">',
        'after_widget' => '</div>',
        'before_title' => '<h3>',
        'after_title' => '</h3>',
    )
);

add_theme_support('post-thumbnails');

function shortcode_twitter() {
    return '<a href="http://twitter.com/username">@username</a> - Follow me!';
}

add_shortcode('twitter', 'shortcode_twitter');