docs: def __retrieve_data(self):
          """Read more data from the file."""
  
          if self.__eof is True:
              return b''
  
          logging.debug("Reading another block.")        
          block = self.read(self.__block_size)
          if block == b'':
              self.__log.debug("We've encountered the EOF.")
              self.__eof = True
  
          return block