public function startUploadSession($dropboxFile, $chunkSize = -1, $close = false)
    {
        //Make Dropbox File with the given chunk size
        $dropboxFile = $this->makeDropboxFile($dropboxFile, $chunkSize);

        //Set the close param
        $params = [
            'close' => $close ? true : false,
            'file' => $dropboxFile
        ];

        //Upload File
        $file = $this->postToContent('/files/upload_session/start', $params);
        $body = $file->getDecodedBody();

        //Cannot retrieve Session ID
        if (!isset($body['session_id'])) {
            throw new DropboxClientException("Could not retrieve Session ID.");
        }

        //Return the Session ID
        return $body['session_id'];
    }