An opaque structure representing iteration in undefined order over a set of integers.
Must be initialized with init.
Before 0.11.16, this type was called TpIntSetFastIter, which is now a backwards compatibility typedef.
Usage is similar to GenericSetIter:
TpIntsetFastIter iter;
guint element;
tp_intset_fast_iter_init (&iter, intset);
while (tp_intset_fast_iter_next (&iter, &element))
{
printf ("%u is in the intset\n", element);
}