10 for in range 10 for in range forward left 90 10 10 20 penup goto pe

n = 10
x,y =0,0
for i in range(10):
    for j in range(4):
        a.forward(n)
        a.left(90)
    x -= 10
    y -= 10
    n += 20
    a.penup()
    a.goto(x,y)
    a.pendown()