Draw a Koch curve. See details: Koch curve

  [ $ "turtleduck.qky" loadfile ] now!
 
  [ $ "" swap witheach 
      [ nested quackery join ] ]    is expand ( $ --> $ )
 
  [ $ "FRFLLFRF" ]                  is F      ( $ --> $ )
 
  [ $ "L" ]                         is L      ( $ --> $ )
 
  [ $ "R" ]                         is R      ( $ --> $ )
 
  $ "FLLFLLF"
 
  4 times expand
 
  turtle
  witheach
    [ dup char F = iff 
        [ drop 3 1 walk ] done
      char L = iff
        [ -1 6 turn ] done
       1 6 turn ]