private function writeTGTtoFile($tgtStorageLocation, $tgt)
    {
        $tgtStorageData = [
            'TGT' => $tgt,
            'username' => $this->casUsername,
            'server' => $this->casServer,
            'context' => $this->casRESTcontext,
            'saved' => time()
        ];

        file_put_contents($tgtStorageLocation, json_encode($tgtStorageData));
    }