up and down up and down
up and down up and down .
u p WORD_BOUNDARY a n d WORD_BOUNDARY d o̞ w n WORD_BOUNDARY u p WORD_BOUNDARY a n d WORD_BOUNDARY d o̞ w n WORD_BOUNDARY
u p WORD_BOUNDARY a n d WORD_BOUNDARY d o w n WORD_BOUNDARY u p WORD_BOUNDARY a n d WORD_BOUNDARY d o w n WORD_BOUNDARY . WORD_BOUNDARY