public function isVirtual($path): bool
    {
        $parts = explode(':', $path, 2);

        list($alias) = $parts;
        $alias = $this->cleanAlias($alias);
        if (!array_key_exists($alias, $this->paths) && $this->prefix($path) !== null) {
            return false;
        }

        return count($parts) === 2;
    }