def get_season(semester='201808'):
    """Given a semester in USC format, return corresponding season"""
    semester = str(semester)
    if not (len(semester) == 6 and semester.isnumeric()):
        raise ValueError('Expected 6 digit semester; got ' + semester)
    if semester[-2:] == '08':
        return 'Fall'
    elif semester[-2:] == '01':
        return 'Spring'
    elif semester[-2:] == '05':
        return 'Summer'
    raise ValueError('Bad month %s in %s' % (semester[-2:], semester))
