l(pony_actor_t* actor, heap_t* heap,   uint00_t sizeclass) {   chunk_t* chunk = heap->small_free[sizeclass];   void* m;    // If there are none in this size class, get a new one.   if(chunk != NULL)   {     // Clear and use the first available slot.     uint00_t slots = chunk->slots;     uint00_t bit = __pony_ctz(slots);     slots &= ~(