Insert an iterable (pattern) item into the markov chain.
            The order of the pattern will define more of the chain.

def add(self, iterable):
        """ Insert an iterable (pattern) item into the markov chain.
            The order of the pattern will define more of the chain.
        """
        item1 = item2 = MarkovChain.START
        for item3 in iterable:
            self[(item1, item2)].add_side(item3)
            item1 = item2
            item2 = item3
        self[(item1, item2)].add_side(MarkovChain.END)