'Merge duplicate items. See ``_merge_items`` and ``_merge_albums``
for the relevant strategies.'

def _merge(self, objs):

    kind = (Item if all((isinstance(o, Item) for o in objs)) else Album)
    if (kind is Item):
        objs = self._merge_items(objs)
    else:
        objs = self._merge_albums(objs)
    return objs
