tml_get_registration_type()

function tml_get_registration_type() {
    $registration_type = get_site_option( 'tml_registration_type', 'default' );

    /**
     * Filter the registration type.
     *
     * @since 7.0
     *
     * @param string $registration_type The registration type.
     */
    return apply_filters( 'tml_get_registration_type', $registration_type );
}

View src/includes/options.php, line 144 on GitHub