if (!allow_duplicates && slot < leaf->slotuse && key_equal(key, leaf->slotkey[slot])) {
return std::pair<iterator, bool>(iterator(leaf, slot), false);
if (!allow_duplicates && slot < leaf->slotuse && key_equal(key, leaf->slotkey[slot])) {
return std::pair<iterator, bool>(iterator(leaf, slot), false);