nxt = container_of_var(i->member.next, i, member); \
&i->member != &(h)->n; \
i = nxt, nxt = container_of_var(i->member.next, i, member))
nxt = container_of_var(i->member.next, i, member); \
&i->member != &(h)->n; \
i = nxt, nxt = container_of_var(i->member.next, i, member))