code: def read_block(self, block):
          
          if block < 0 or block > 255:
              raise ValueError("invalid block number")
          log.debug("read block {0}".format(block))
          cmd = "\x02" + chr(block) + 8 * chr(0) + self.uid
          return self.transceive(cmd)[1:9]
docs: Read an 8-byte data block at address (block * 8).