def indelDelta(ref, alt):
    """ Detects the inserted or deleted bases of an indel"""
    if len(alt) > len(ref):
        return [alt.replace(ref, '', 1), str('INS')]
    elif len(alt) < len(ref):
        return [ref.replace(alt, '', 1), str('DEL')]
    else:
        return ['', '']
