Set the watchlist to the given tubes

        :param tubes: A list of tubes to watch

        Automatically un-watches any tubes that are not on the target list

def watchlist(self, tubes):
        """Set the watchlist to the given tubes

        :param tubes: A list of tubes to watch

        Automatically un-watches any tubes that are not on the target list
        """
        tubes = set(tubes)
        for tube in tubes - self._watchlist:
            self.watch(tube)
        for tube in self._watchlist - tubes:
            self.ignore(tube)