Gaufrette\Adapter\PhpseclibSftp::isDirectory PHP Method

    public function isDirectory($key)
    {
        $this->initialize();
        $pwd = $this->sftp->pwd();
        if ($this->sftp->chdir($this->computePath($key))) {
            $this->sftp->chdir($pwd);
            return true;
        }
        return false;
    }