# draw upper right quadrant
fd 100
rt 90
fd 100
rt 90
fd 100
rt 90
fd 100

# draw upper left quadrant
fd 100 rt 90
fd 100 rt 90
fd 100 rt 90
fd 100

# draw lower left quadrant
fd 100 rt 90 fd 100 rt 90
fd 100 rt 90 fd 100

# draw lower right quadrant
fd 100 rt 90 fd 100 rt 90 fd 100 rt 90 fd 100 rt 90