arr arr arr arr
arr arr arr arr .
ɐ r ɾ WORD_BOUNDARY ɐ r ɾ WORD_BOUNDARY ɐ r ɾ WORD_BOUNDARY ɐ r ɾ WORD_BOUNDARY
a r r WORD_BOUNDARY a r r WORD_BOUNDARY a r r WORD_BOUNDARY a r r WORD_BOUNDARY . WORD_BOUNDARY