'Given a list of rooms and a token, return rooms where there may have
been changes.
Args:
room_ids (list)
from_key (str): The room_key portion of a StreamToken'

def get_rooms_that_changed(self, room_ids, from_key):

    from_key = RoomStreamToken.parse_stream_token(from_key).stream
    return set((room_id for room_id in room_ids if self._events_stream_cache.has_entity_changed(room_id, from_key)))
