.: skip  .w@ lmask - .w@ 2 and 0!=me ;
.: size  s1 @ s0 @ - ;
.: save  s1 @ w@ x:8003 and or s1 @ w! ;
.: step  s0 @ s1 ! ;
.: wipe  skip size save step .w@ lmask 0!=me ;
: .wipe  path @ @ lfa dup { wipe 2 } ;