def query_binary_data(self, target, display_mask, attr):
    """Return binary data"""
    reply = NVCtrlQueryBinaryDataReplyRequest(display=self.display,
                                              opcode=self.display.get_extension_major(extname),
                                              target_id=target.id(),
                                              target_type=target.type(),
                                              display_mask=display_mask,
                                              attr=attr)
    if not reply._data.get('flags'):
        return None
    return reply._data.get('data')
Return binary data