def nla_padlen(payload):
return int(nla_total_size(payload) - nla_attr_size(payload))<EOL>
Return length of padding at the tail of the attribute.

    https://github.com/thom311/libnl/blob/libnl3_2_25/lib/attr.c#L91

    +------------------+- - -+- - - - - - - - - +- - -+
    | Attribute Header | Pad |     Payload      | Pad |
    +------------------+- - -+- - - - - - - - - +- - -+
                                                 <--->

    Positional arguments:
    payload -- payload length of attribute (integer).

    Returns:
    Length of padding in bytes (integer).