def nla_get_u64(nla):
    """Return value of 64 bit integer attribute as an int().

    https://github.com/thom311/libnl/blob/libnl3_2_25/lib/attr.c#L649

    Positional arguments:
    nla -- 64 bit integer attribute (nlattr class instance).

    Returns:
    Payload as an int().
    """
    tmp = c_uint64(0)
    if nla and nla_len(nla) >= sizeof(tmp):
        tmp = c_uint64.from_buffer(nla_data(nla)[:SIZEOF_U64])
    return int(tmp.value)