protected function getExistingMigrationsWarning(array $existingMigrations)
    {
        if (count($existingMigrations) > 1) {
            $base = "Laratrust upgrade migrations already exist.\nFollowing files were found: ";
        } else {
            $base = "Laratrust upgrade migration already exists.\nFollowing file was found: ";
        }

        return $base . array_reduce($existingMigrations, function ($carry, $fileName) {
            return $carry . "\n - " . $fileName;
        });
    }