code: def add_collection(collection,
                     cache_size=1000,
                     cache_cls=LRUCache,
                     **cache_args):
      
      assert collection not in _db
      cache = cache_cls(maxsize=cache_size,
                        missing=lambda id: load_object(collection, id),
                        **cache_args)
      _db[collection] = aadict(cache=cache, indexes={})
docs: Add a collection named ``collection``.