Quadrati 2 – 3 – 4

import math
import turtle

WIDTH  = 500
HEIGHT = 500
r2     = math.sqrt(2)/2
DIM1   = 0.8*HEIGHT
DIM1_2 = DIM1/2
DIM2   = r2*DIM1
PASSI  = [ DIM1, DIM1, DIM1, DIM1_2, DIM2,
           DIM2, DIM2, DIM2, DIM1_2 ]
ANGOLI = [  0, 90, 90, 90, 45, 
           90, 90, 90, 45 ]

turtle.setup(WIDTH, HEIGHT)
turtle.title("Un solo tratto")
turtle.shape('turtle')
turtle.pencolor('red')
turtle.bgcolor('pink')
turtle.pensize(4)

turtle.penup()
turtle.setposition(-DIM1_2, -DIM1_2)
turtle.pendown()

for angolo, passo in zip(ANGOLI, PASSI):
    turtle.left(angolo)
    turtle.forward(passo)

...
DIM1   = 0.8*HEIGHT
DIM2   = r2*DIM1
DIM3   = r2*DIM2
DIM1_2 = DIM1/2
DIM2_2 = DIM2/2
...

...
DIM1   = 0.8*HEIGHT
DIM2   = r2*DIM1
DIM3   = r2*DIM2
DIM4   = r2*DIM3
...