@validate(addr=int, cmd=int)<EOL><INDENT>def read_byte_data(self, addr, cmd):<DEDENT>
self._set_addr(addr)<EOL>res = SMBUS.i2c_smbus_read_byte_data(self._fd, ffi.cast("<STR_LIT>", cmd))<EOL>if res == -<NUM_LIT:1>:<EOL><INDENT>raise IOError(ffi.errno)<EOL><DEDENT>return res<EOL>
read_byte_data(addr, cmd) -> result

        Perform SMBus Read Byte Data transaction.