def unpack(self, format_text):
        """Unpack bytes using struct modules format

        :param format_text: struct's module format
        :type  format_text: :class:`str`
        :return data: result from :func:`struct.unpack_from`
        :rtype: :class:`tuple`
        """
        data = _unpack_from(format_text, self.data, self.offset)
        self.offset += _calcsize(format_text)
        return data
Unpack bytes using struct modules format

        :param format_text: struct's module format
        :type  format_text: :class:`str`
        :return data: result from :func:`struct.unpack_from`
        :rtype: :class:`tuple`