TO L3
  CS
  PU SETX -100 SETY -100 PD
  MAKE "B 7
  REPEAT 7[L2 :B  MAKE "B :B-1]
  L1    
END
TO L1
   SETPC 0   LT 60 
   REPEAT 2[FD 20 RT 120 FD 20 RT 60] RT 60
   SETPC 11
   REPEAT 2[LT 60 FD 20 LT 120 FD 20 ]
   PU LT 120 FD 10 PD FILL BK 10 RT 120
   SETPC 12 
   REPEAT 2[RT 60 FD 20 RT 120 FD 20]
   PU RT 120 FD 10 PD FILL BK 10 LT 120
END

TO L2 :A
  REPEAT :A[L1 PU RT 60 FD 20 RT 60 FD 20 LT 120 PD] L1
  REPEAT :A[PU LT 60 FD 20 LT 60 FD 20 RT 120 PD]
  PU RT 60 FD 20 LT 60 FD 20 PD
END



