def p_track_file(t):
    """track_flag : FILE STRING start
                  | AUDIOFILE STRING start
                  | FILE STRING start length
                  | AUDIOFILE STRING start length"""
    from audiotools.toc import TOCFlag_FILE
    if len(t) == 4:
        t[0] = TOCFlag_FILE(type=t[1], filename=t[2], start=t[3])
    else:
        t[0] = TOCFlag_FILE(type=t[1], filename=t[2], start=t[3], length=t[4])
