code: def upload(self, block_num):
          
          logger.debug("db_upload block_num: %s" % (block_num))
  
          block_type = snap7.snap7types.block_types['DB']
          _buffer = buffer_type()
          size = c_int(sizeof(_buffer))
  
          result = self.library.Cli_Upload(self.pointer, block_type, block_num,
                                           byref(_buffer), byref(size))
  
          check_error(result, context="client")
          logger.info('received %s bytes' % size)
          return bytearray(_buffer)
docs: Uploads a block body from AG
  
          :param data: bytearray