a va va va va
a va va va va .
a WORD_BOUNDARY ʋ a WORD_BOUNDARY ʋ a WORD_BOUNDARY ʋ a WORD_BOUNDARY ʋ a WORD_BOUNDARY
a WORD_BOUNDARY v a WORD_BOUNDARY v a WORD_BOUNDARY v a WORD_BOUNDARY v a WORD_BOUNDARY . WORD_BOUNDARY