def get_letters_iterable( word ):
    """ splits the word into a character-list of tamil/english
    characters present in the stream """
    WLEN,idx = len(word),0

    while (idx < WLEN):
        c = word[idx]
        #print(idx,hex(ord(c)),len(ta_letters))
        if c in uyir_letter_set or c == ayudha_letter:
            idx = idx + 1
            yield c
        elif c in grantha_agaram_set:
            if idx + 1 < WLEN and word[idx+1] in all_symbol_set:
                c2 = word[idx+1]
                idx = idx + 2
                yield (c + c2)
            else:
                idx = idx + 1
                yield c
        else:
            idx = idx + 1
            yield c
    return
splits the word into a character-list of tamil/english
    characters present in the stream