public void Detach(byte[] sourceStreamId, byte[] streamIdToDetach, long detachedSince) { ActivityStream stream; if (activityFeedStore.TryGetValue(sourceStreamId, out stream)) { var detaching = stream.AttachedStreams.Where(x => ByteArrayHelper.Compare(x.StreamId, streamIdToDetach)).Single(); detaching.ExpiresAt = detachedSince; } }