Yields each object ID in the given ``collection``.
    The objects are not loaded.

def each_object_id(collection):
    """Yields each object ID in the given ``collection``.
    The objects are not loaded."""
    c_path = collection_path(collection)
    paths = glob('%s/*.%s' % (c_path, _ext))
    for path in paths:
        match = regex.match(r'.+/(.+)\.%s$' % _ext, path)
        yield match.groups()[0]