Save extra user fields

# Save extra user fields

function czystespalanie__registration_save( $user_id ) {

    if ( isset( $_POST['first_name'] ) or isset( $_POST['first_name_2'] ))
        update_user_meta( $user_id, 'first_name', sanitize_text_field( $_POST['first_name'] ));
    if ( isset( $_POST['last_name'] ) )
        update_user_meta( $user_id, 'last_name', sanitize_text_field( $_POST['last_name'] ));
    // if ( isset( $_POST['tel'] ) )
        // update_user_meta( $user_id, 'tel', sanitize_text_field( $_POST['tel'] ));
}
add_action( 'user_register', 'czystespalanie__registration_save', 10, 1 );