he+eh he+eh da
he eh he eh da .
h ɛ WORD_BOUNDARY  ɛ h WORD_BOUNDARY h ɛ WORD_BOUNDARY  ɛ h WORD_BOUNDARY d a WORD_BOUNDARY
h e WORD_BOUNDARY e h WORD_BOUNDARY h e WORD_BOUNDARY e h WORD_BOUNDARY d a WORD_BOUNDARY