def _setOb(self, object_id, obj):
   """
     Update portal_skins cache with the new files.
   """
   Folder._setOb(self, object_id, obj)
   portal_skins = getattr(self, 'portal_skins', None)
   if portal_skins is None:
     return
   portal_skins = self.getPortalObject().portal_skins
   _updateCacheEntry = getattr(portal_skins.aq_base, '_updateCacheEntry', None)
   if _updateCacheEntry is None:
     return
   _updateCacheEntry(self.id, object_id)