python timecode to frame

framerate = 60

def _seconds(value):
    if isinstance(value, str):  # value seems to be a timestamp
        _zip_ft = zip((3600, 60, 1, 1/framerate), value.split(':'))
        return sum(f * float(t) for f,t in _zip_ft)
    elif isinstance(value, (int, float)):  # frames
        return value / framerate
    else:
        return 0

def _timecode(seconds):
    return '{h:02f}:{m:02f}:{s:02f}:{f:02f}'.format(h=int(seconds/3600),m=int(seconds/60%60),s=int(seconds%60),f=round((seconds-int(seconds))*framerate))

def _frames(seconds):
    return seconds * framerate

def timecode_to_frames(timecode, start=None):
    return _frames(_seconds(timecode) - _seconds(start))

def frames_to_timecode(frames, start=None):
    return _timecode(_seconds(frames) + _seconds(start))