Prepare sequences.

        qval=None: split text by words
        qval=1: do not split sequences. For text this is mean comparing by letters.
        qval>1: split sequences by q-grams

def _get_sequences(self, *sequences):
        """Prepare sequences.

        qval=None: split text by words
        qval=1: do not split sequences. For text this is mean comparing by letters.
        qval>1: split sequences by q-grams
        """
        # by words
        if not self.qval:
            return [s.split() for s in sequences]
        # by chars
        if self.qval == 1:
            return sequences
        # by n-grams
        return [find_ngrams(s, self.qval) for s in sequences]