def version_specific(version, v3_subcon, v4_subcon):
    """
    There are some differences in the parsing structure between v3 and v4. Some fields are different length and some
    exist only in one of the versions. this returns the relevant parsing structure by version
    :param version: int 3 or 4
    :param v3_subcon: the parsing struct if version is 3
    :param v4_subcon: the parsing struct if version is 4
    """
    if version == 3:
        return v3_subcon
    else:
        return v4_subcon