In a C-like notation this would look like this:

pb = lookup_pb(page, UB);

if (pb != NULL) {

list_add_tail(pb, page.pb_list);

page.pb_list.first = head.next;

Shift increment essentially means “take one half of the currently held fraction and give it to the newbie”.

{{Note|cases when <code>page.pb_list</code> is becoming empty on adding a reference, or becoming empty on removing references are skipped to simplify the code examples.}}