'Initialise with 1,2 or 3 sequences to compare'

def __init__(self, *sequences):

    self.num_sequences = len(sequences)
    self.seqlength = [0, 0, 0]
    for (i, s) in enumerate(sequences):
        self.seqlength[i] = len(s)
    if ((len(sequences) == 0) or (len(sequences) == 1)):
        self.diffs = [[], []]
    elif (len(sequences) == 2):
        seq0 = IncrementalSequenceMatcher(None, sequences[1], sequences[0]).get_difference_opcodes()
        self.diffs = [seq0, []]
    elif (len(sequences) == 3):
        seq0 = IncrementalSequenceMatcher(None, sequences[1], sequences[0]).get_difference_opcodes()
        seq1 = IncrementalSequenceMatcher(None, sequences[1], sequences[2]).get_difference_opcodes()
        self.diffs = (seq0, seq1)
    else:
        raise ValueError(('Bad    number    of    arguments    to    Differ    constructor    (%i)' % len(sequences)))
