docs: def set_many(self, data, expiry=DEFAULT_EXPIRY):
          """
          Set a bunch of values in the cache at once from a dict of key/value
          pairs.  For certain backends (memcached), this is much more efficient
          than calling set() multiple times.
          If timeout is given, use that timeout for the key; otherwise use the
          default cache timeout.
          On backends that support it, return a list of keys that failed
          insertion, or an empty list if all keys were inserted successfully.
          """
          for key, value in data.items():
              self.set(key, value, expiry=expiry)
          return []