Euler's identity, but with tau

tauler.py

#!/usr/bin/env python3

import math
import numpy
from turtle import *


def tauler(unit):
    tau = math.pi * 2
    d_r_90 = tau / 4
    arc_length = tau * unit
    unit_inv = 1 / unit

    penup()
    forward(unit)
    left(d_r_90)
    pendown()

    for _ in numpy.linspace(start=0, stop=arc_length, num=math.floor(arc_length)):
        forward(1)
        left(unit_inv)

    left(d_r_90)
    pencolor('green')

    for _ in range(unit * 2):
        forward(0.5)


if __name__ == '__main__':
    bgcolor('black')
    hideturtle()
    title("Euler's identity")
    speed('fastest')
    pencolor('white')
    width(2)
    radians()

    tauler(100)

    exitonclick()