get_weekstartend example

if ( ! $results ) {
            $results = $wpdb->get_results( $query );
            wp_cache_set( $key, $results, 'post-queries' );
        }
        $arc_w_last = '';
        if ( $results ) {
            $after = $parsed_args['after'];
            foreach ( (array) $results as $result ) {
                if ( $result->week != $arc_w_last ) {
                    $arc_year       = $result->yr;
                    $arc_w_last     = $result->week;
                    $arc_week       = get_weekstartend( $result->yyyymmdd, get_option( 'start_of_week' ) );
                    $arc_week_start = date_i18n( get_option( 'date_format' ), $arc_week['start'] );
                    $arc_week_end   = date_i18n( get_option( 'date_format' ), $arc_week['end'] );
                    $url            = add_query_arg(
                        array(
                            'm' => $arc_year,
                            'w' => $result->week,
                        ),
                        home_url( '/' )
                    );
                    if ( 'post' !== $parsed_args['post_type'] ) {
                        $url = add_query_arg( 'post_type', $parsed_args['post_type'], $url );
                    }