def shlok_lengths(shlokasSyllables):
    """Return a dictionary of lengths of syllables of shlokas in shlokasSyllables.
    Input
    shlokasSyllables : list of lists of syllables in every shloka
    Ouptuts
    shlokLengths : dictionary of shlok_lengths:shlok_numbers
    """
    shlokLengths = {}
    for i, shlokSyllables in enumerate(shlokasSyllables):
            lenSyllables = len(shlokSyllables)
            if lenSyllables not in shlokLengths.keys():
                shlokLengths[lenSyllables] = [i]
            else:
                shlokLengths[lenSyllables].append(i)
    return shlokLengths