decode Olympus SpecialMode tag in MakerNote

def special_mode(v):
    """decode Olympus SpecialMode tag in MakerNote"""
    mode1 = {
        0: 'Normal',
        1: 'Unknown',
        2: 'Fast',
        3: 'Panorama',
    }
    mode2 = {
        0: 'Non-panoramic',
        1: 'Left to right',
        2: 'Right to left',
        3: 'Bottom to top',
        4: 'Top to bottom',
    }
    if not v or (v[0] not in mode1 or v[2] not in mode2):
        return v
    return '%s - sequence %d - %s' % (mode1[v[0]], v[1], mode2[v[2]])