The type 'type_info' has a member function called 'before'.

If it were also to have the following:

bool operator<(type_info const &arg)
{
    return this->before(arg);
}

then this would mean that we could have an ordered container of
'type_info', e.g.

    std::set<type_info> myset;

Presently this is only possible by specialising 'std::set' with a
custom comparator.