public function widget( $args, $instance ) {
    $title = ! empty( $instance['title'] ) ? $instance['title'] : '';

    
/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
    $title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

    echo $args['before_widget'];
    if ( $title ) {
      echo $args['before_title'] . $title . $args['after_title'];
    }
    if ( 0 === self::$instance ) {
      echo '<div id="calendar_wrap" class="calendar_wrap">';
    } else {
      echo '<div class="calendar_wrap">';
    }
    get_calendar();
    echo '</div>';
    echo $args['after_widget'];

    ++self::$instance;
  }