code: def get_letters_iterable( word ):
      
      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
docs: splits the word into a character-list of tamil/english
      characters present in the stream