bbp_get_topic_class( int $topic_id,  $classes = array() )

	function bbp_get_topic_class( $topic_id = 0, $classes = array() ) {
		$bbp       = bbpress();
		$topic_id  = bbp_get_topic_id( $topic_id );
		$count     = isset( $bbp->topic_query->current_post ) ? $bbp->topic_query->current_post : 1;
		$classes   = (array) $classes;
		$classes[] = ( (int) $count % 2 )                    ? 'even'         : 'odd';
		$classes[] = bbp_is_topic_sticky( $topic_id, false ) ? 'sticky'       : '';
		$classes[] = bbp_is_topic_super_sticky( $topic_id  ) ? 'super-sticky' : '';
		$classes[] = 'bbp-parent-forum-' . bbp_get_topic_forum_id( $topic_id );
		$classes[] = 'user-id-' . bbp_get_topic_author_id( $topic_id );
		$classes   = array_filter( $classes );
		$classes   = get_post_class( $classes, $topic_id );
		$classes   = apply_filters( 'bbp_get_topic_class', $classes, $topic_id );
		$retval    = 'class="' . implode( ' ', $classes ) . '"';

		return $retval;
	}