doSiftUp

        fn doSiftUp(self: *Self, start_index: usize, target_order: Order) void {
            var child_index = start_index;
            while (child_index > 2) {
                const grandparent_index = grandparentIndex(child_index);
                const child = self.items[child_index];
                const grandparent = self.items[grandparent_index];

                // If the grandparent is already better or equal, we have gone as far as we need to
                if (compareFn(self.context, child, grandparent) != target_order) break;

                // Otherwise swap the item with it's grandparent
                self.items[grandparent_index] = child;
                self.items[child_index] = grandparent;
                child_index = grandparent_index;
            }
        }