public function connect($username , $password)
    {
        if ( ! $this->isConnected ) {
            try {
                $this->client->LogIn([ 'username' => $username , 'password' => $password ]);
                $this->isConnected = true;
            } catch ( SoapFault $ex ) {
                throw new ConnectException('Either an error occured when connecting to Livedocx, or the credentials you provided are wrong' , $ex);
            }
        }
        return $this;
    }