Python使用turtle画棋盘格

import turtle
turtle.speed(0.2)
#边框
for i in range(4):
    turtle.fd(200)
    turtle.left(90)
#横向画线    
x = 0
a = 25
for y in range(25, 200, a):
    turtle.penup()
    turtle.goto(x,y)
    turtle.pendown()
    turtle.fd(200)
#纵向画线    
y = 200
turtle.right(90)
for x in range(25, 200, a):
    turtle.penup()
    turtle.goto(x,y)
    turtle.pendown()
    turtle.fd(200)
#填充偶数格
for x in range(0, 200, 2*a):
    for y in range(25, 200, 2*a):
        turtle.penup()
        turtle.goto(x,y)
        turtle.pendown()
        turtle.begin_fill()
        for z in range(4):
            turtle.fd(25)
            turtle.left(90)
        turtle.end_fill()
#填充奇数格
for x in range(25, 201, 2*a):
    for y in range(50, 201, 2*a):
        turtle.penup()
        turtle.goto(x,y)
        turtle.pendown()
        turtle.begin_fill()
        for z in range(4):
            turtle.fd(25)
            turtle.left(90)
        turtle.end_fill()
turtle.hideturtle()