arco-íris

import turtle
import colorsys

def draw_one_color_arc(x, y, r, pensize, color):
turtle.up()
turtle.goto(x + r, y)
turtle.down()
turtle.seth(90)
turtle.pensize(pensize)
turtle.pencolor(color)
turtle.circle(r, 180)

# Setup
turtle.speed(0)
turtle.hideturtle()
turtle.bgcolor('skyblue')
turtle.title('Arco-íris')
turtle.setup(800, 600)

# Rainbow parameters
num_colors = 70
radius = 300
penwidth = 20 * 7 / num_colors
hue = 0

# Draw rainbow
for i in range(num_colors):
r, g, b = colorsys.hsv_to_rgb(hue, 1, 1)
turtle.colormode(1.0)
draw_one_color_arc(0, -150, radius, penwidth, (r, g, b))
radius -= (penwidth - 1)
hue += 1 / num_colors

turtle.done()