import turtle as tt
from random import choice

def turtle_07():
    """Draw an octagon that uses a different colour (randomly selected from a
    list of six possible colours) for each line."""
    colors = ['yellow', 'orange', 'red', 'green', 'magenta']

    def rand_color():
        return choice(colors)

    tt.bgcolor("black")
    tt.pensize(10)
    tt.speed(2)
    tt.up()
    tt.back(100)
    tt.left(90)
    tt.forward(250)
    tt.right(90)
    tt.down()

    for _ in range(8):
        tt.color(rand_color())
        tt.forward(200)
        tt.right(45)

    tt.exitonclick()