* ``items()`` would return the full list of calendars.
* ``items([list of codes...])`` would return a dictionary of calendars whose codes are in the registry. Unkown codes would be skipped. Sub-regions codes would be allowed (e.g.: ``items(['CA-AB', 'AU-NT'])`` would return the Canada Alberta & Australia Northern Territory calendars)
* ``items([list of codes...], include_subregions=True)`` same as above, except that you would get also subregions when they exist.
Bruno Bord
Christopher Wittlinger