import turtle
from random import randint
t = turtle.Turtle()
t.colormode(255)
t.speed(50)
x = 1
while x < 400:
r = randint(0,255) #makes variables r,g,b whose value is an integer,
g = randint(0,255) # which is between 0 and 255. It is random, and
b = randint(0,255) # changes every time the loop runs
t.pencolor(r,g,b)
t.forward(50 + x)
t.right(90.911)
x = x+1

Py2.x