Move All Posts From One Author to Another (WP-CLI)

if ( ! defined( 'WP_CLI' ) || ! WP_CLI ) {
    return;
}

WP_CLI::add_command( 'reassign-posts', function ( $args, $assoc_args ) {
    $find = function ( $value ) {
        $field = is_numeric( $value ) ? 'id' : ( is_email( $value ) ? 'email' : 'login' );
        $user  = get_user_by( $field, $value );
        if ( ! $user ) {
            WP_CLI::error( sprintf( 'User "%s" not found.', $value ) );
        }
        return $user;
    };

    $from = $find( $args[0] );
    $to   = $find( $args[1] );

    $ids = get_posts( array(
        'author'         => $from->ID,
        'post_type'      => isset( $assoc_args['post_type'] ) ? array_map( 'sanitize_key', explode( ',', $assoc_args['post_type'] ) ) : 'any',
        'post_status'    => 'any',
        'posts_per_page' => -1,
        'fields'         => 'ids',
        'no_found_rows'  => true,
    ) );

    if ( ! empty( $assoc_args['dry-run'] ) ) {
        WP_CLI::log( sprintf( '%d posts would move from %s to %s.', count( $ids ), $from->user_login, $to->user_login ) );
        return;
    }

    $progress = WP_CLI\Utils\make_progress_bar( 'Reassigning', count( $ids ) );
    foreach ( $ids as $id ) {
        wp_update_post( array( 'ID' => $id, 'post_author' => $to->ID ) );
        $progress->tick();
    }
    $progress->finish();

    WP_CLI::success( sprintf( 'Moved %d posts from %s to %s.', count( $ids ), $from->user_login, $to->user_login ) );
}, array(
    'shortdesc' => 'Moves all posts from one author to another.',
    'synopsis'  => array(
        array( 'type' => 'positional', 'name' => 'from', 'description' => 'Current author (ID, login or email).' ),
        array( 'type' => 'positional', 'name' => 'to', 'description' => 'New author (ID, login or email).' ),
        array( 'type' => 'assoc', 'name' => 'post_type', 'optional' => true ),
        array( 'type' => 'flag', 'name' => 'dry-run', 'optional' => true ),
    ),
) );