[ $ "bigrat.qky" loadfile ] now!

  [ 1 & not ]                  is even     (     n --> b     )

  [ nip 1 = ]                  is vint     (   n/d --> b     )

  [ [ dup even while
      1 >> again ]
    1 = ]                      is powerof2 (     n --> b     )

  [ 0 swap
    [ dup even while
      dip 1+
      1 >> again ]
    drop ]                     is lowbit   (     n --> n     )

  [ [] swap nest$
    witheach
      [ char / over find
        space unrot poke
        build nested join ] ]  is parse$   (     $ --> [     )

  [ stack ]                    is program  (     s -->       )

  [ true temp put
    witheach
      [ do 2over v*
        2dup vint iff
          [ false temp replace
            conclude ]
         else 2drop ]
      2swap 2drop
      temp take ]              is run      ( n/d [ --> n/d b )

  [ stack ]                    is primes   (       --> s     )

  $ "17/91 78/85 19/51 23/38 29/33 77/29 95/23"
  $ " 77/19 1/17 11/13 13/11 15/14 15/2 55/1" join
  parse$ program put

  2 n->v
  15 times
    [ program share run
      drop over echo sp ]
  cr
  2drop
  2 n->v
  [] primes put
  [ program share run
    drop over dup powerof2 iff
      [ lowbit primes take
        swap join primes put ]
    else drop
    primes share size 20 = until ]
  2drop
  primes take echo

  program release