Returns a string containing the authorization header used to authenticate
        with GenePattern. This string is included in the header of subsequent
        requests sent to GenePattern.

def authorization_header(self):
        """
        Returns a string containing the authorization header used to authenticate
        with GenePattern. This string is included in the header of subsequent
        requests sent to GenePattern.
        """
        return 'Basic %s' % base64.b64encode(bytes(self.username + ':' + self.password, 'ascii')).decode('ascii')