did you look into dstore/Observable and see if that allows you to implement before without having to call directly into the delite/Store API here? If possible this would be preferable. If not I suppose we should create an issue in dstore wich is related to SitePen/dstore/issues/2 but different (i.e. not "provide a Memory store that supports 'before'" but "make Observable be able to deal with stores that supports 'before'").