he+em tar digigitin
he em tar digigitin .
h ɛ WORD_BOUNDARY  ɛ m WORD_BOUNDARY t a r WORD_BOUNDARY d i ɡ i ɡ i t i n WORD_BOUNDARY
h e WORD_BOUNDARY e m WORD_BOUNDARY t a r WORD_BOUNDARY d i g i g i t i n WORD_BOUNDARY