code: def upsert_multi(self, keys, ttl=0, format=None, persist_to=0, replicate_to=0):
          
          return _Base.upsert_multi(self, keys, ttl=ttl, format=format,
                                    persist_to=persist_to,
                                    replicate_to=replicate_to)
docs: Write multiple items to the cluster. Multi version of :meth:`upsert`
  
          :param dict keys: A dictionary of keys to set. The keys are the
              keys as they should be on the server, and the values are the
              values for the keys to be stored.
  
              `keys` may also be a :class:`~.ItemCollection`. If using a
              dictionary variant for item collections, an additional
              `ignore_cas` parameter may be supplied with a boolean value.
              If not specified, the operation will fail if the CAS value
              on the server does not match the one specified in the
              `Item`'s `cas` field.
          :param int ttl: If specified, sets the expiration value
              for all keys
          :param int format: If specified, this is the conversion format
              which will be used for _all_ the keys.
          :param int persist_to: Durability constraint for persistence.
              Note that it is more efficient to use :meth:`endure_multi`
              on the returned :class:`~couchbase.result.MultiResult` than
              using these parameters for a high volume of keys. Using
              these parameters however does save on latency as the
              constraint checking for each item is performed as soon as it
              is successfully stored.
          :param int replicate_to: Durability constraints for replication.
              See notes on the `persist_to` parameter for usage.
          :return: A :class:`~.MultiResult` object, which is a
              `dict`-like object
  
          The multi methods are more than just a convenience, they also
          save on network performance by batch-scheduling operations,
          reducing latencies. This is especially noticeable on smaller
          value sizes.
  
          .. seealso:: :meth:`upsert`