to cforward :distance
  while [:distance > 0]                     ; Go until it's time to stop. ~
   [
    if (xcor * xcor + ycor * ycor) > 10000  ; Check if inside circle. ~
       [penup                               ; If not, "wrap".
        setx -1 * xcor
        sety -1 * ycor
        pendown]
    make "distance :distance-1              ; Decrease distance left to go.
    forward 1
   ]
end