removeSlot

        fn removeSlot(removed_slot: usize, header: *IndexHeader, comptime I: type, indexes: []Index(I)) void {
            const start_index = removed_slot +% 1;
            const end_index = start_index +% indexes.len;

            var last_slot = removed_slot;
            var index: usize = start_index;
            while (index != end_index) : (index +%= 1) {
                const slot = header.constrainIndex(index);
                const slot_data = indexes[slot];
                if (slot_data.isEmpty() or slot_data.distance_from_start_index == 0) {
                    indexes[last_slot].setEmpty();
                    return;
                }
                indexes[last_slot] = .{
                    .entry_index = slot_data.entry_index,
                    .distance_from_start_index = slot_data.distance_from_start_index - 1,
                };
                last_slot = slot;
            }
            unreachable;
        }