public static function generate_labels( $plural_name, $singular_name, $type = 'labels', $gender = 'neuter' ) {
            $gender_map = array( 'm' => 'masculine', 'f' => 'feminine', 'n' => 'neuter' );
            if ( isset( $gender_map[ $gender ] ) ) {
                $gender = $gender_map[ $gender ];
            }