绘制三色彩虹

import turtle

#设置画笔大小为20
turtle.pensize(20)
turtle.left(90)
#设置画笔颜色为红色
turtle.pencolor('red')
turtle.circle(100,180)

turtle.penup()
turtle.goto(0-10,0)
turtle.left(180)
turtle.pendown()
turtle.pencolor("orange")
turtle.circle(100-10,180)

turtle.penup()
turtle.goto(-15,0)
turtle.left(180)
turtle.pendown()
turtle.pencolor("yellow")
turtle.circle(85,180)

turtle.done()