def unpack(self, buff, offset=0):
        """Unpack a binary message into this object's attributes.

        Unpack the binary value *buff* and update this object attributes based
        on the results.

        Args:
            buff (bytes): Binary data package to be unpacked.
            offset (int): Where to begin unpacking.

        Raises:
            Exception: If there is a struct unpacking error.

        """
        try:
            unpacked_data = struct.unpack('!4B', buff[offset:offset+4])
            self._value = '.'.join([str(x) for x in unpacked_data])
        except struct.error as exception:
            raise exceptions.UnpackException('%s; %s: %s' % (exception,
                                                             offset, buff))
Unpack a binary message into this object's attributes.

        Unpack the binary value *buff* and update this object attributes based
        on the results.

        Args:
            buff (bytes): Binary data package to be unpacked.
            offset (int): Where to begin unpacking.

        Raises:
            Exception: If there is a struct unpacking error.