code: func defaultContext(c context.Context) context.Context {
  	c = ds.WithoutTransaction(info.MustNamespace(c, ""))
  	return dscache.AddShardFunctions(c, func(*ds.Key) (shards int, ok bool) {
  		return 0, true
  	})
  }
docs: // defaultContext returns datastore interface configured to use default
  // namespace, escape any current transaction, and don't use dscache (since it
  // may not be available when modifying settings).