def sendFeatureReport(self, report, report_num=0):
        """
        Send a feature report.
        """
        length = len(report) + 1
        buf = ctypes.create_string_buffer(b(struct.pack("B", report_num) + report), length)
        self._ioctl(_HIDIOCSFEATURE(length), buf, True)
        print(_HIDIOCSFEATURE(length))