: BLK! ( -- )
BLK> @ BLK!* @ EXECUTE
0 BLKDTY !
;
: FLUSH BLKDTY @ IF BLK! THEN ;
: BLK@ ( n -- )
DUP BLK> @ = IF DROP EXIT THEN
FLUSH DUP BLK> ! BLK@* @ EXECUTE ;
: BLK!! 1 BLKDTY ! ;