struct DoingTheNastyAllocator(Allocator, size_t chunkSize) {
    enum size_t alignment = 16;

    Allocator allocator;

    void[] heap;
    void[] allocate(size_t size) {
        immutable actSize = (size + 15) & ~15;

        if (actSize <= heap.length) {
            void[] buf = heap[0..size];
            heap = heap[actSize..$];
            return buf;
        }

        if (actSize > chunkSize)
            return allocator.alloc(size);

        void[] buf = allocator.alloc(chunkSize);
        heap = buf[actSize..$];
        return buf[0..size];
    }

    void deallocate(void[] buf) { /* lol */ }
    void deallocateAll() { allocator.deallocateAll() } // lol here too?

    static typeof(this) it = typeof(this)();
}