import turtle

pen = turtle.Pen()
pen.speed(10)

width = 30  # 格子寬度
count = 18  # 橫向縱向格子數

o = width * count / 2  # 開始繪製原點

for i in range(count + 1):
    pen.penup()
    pen.goto(-o, o - i * width)
    pen.pendown()
    pen.goto(o, o - i * width)


pen.right(90)
for i in range(count + 1):
    pen.penup()
    pen.goto(
 
-o + i * width, o)
    pen.pendown()
    pen.goto(-o + i * width, -o)

pen.hideturtle()
turtle.done()