问在导出的PostScript文件中显示隐藏的海龟

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import turtle
from itertools import combinations
from math import pi, cos, sin

def points(n, r):
    """Generate a list of points making the vertices of a regular n-gon centred at the origin"""
    return [(r * cos(2 * pi * i / n), r * sin(2 * pi * i / n)) for i in range(n)]

def rotate(points, a):
    """Rotate a given list of points by the angle a (in radians) about the origin"""
    return [(x*cos(a) - y*sin(a), y*cos(a) + x*sin(a)) for x, y in points]

def scale(points, s):
    """Scale a given list of points by the scale factor s about the origin"""
    return [(x*s, y*s) for x, y in points]

def complete_poly(points, n):
    """Draw a connected graph using the points specified"""
    t.pu()
    t.goto(points[-1])
    t.pd()
    for ix, iy in combinations(range(n), 2):
        t.goto(points[ix])
        t.goto(points[iy])

def incomplete_poly(points, n):
    """Draw a graph connecting only nodes seperating by a single node or none"""
    t.pu()
    t.goto(points[-1])
    t.pd()
    for inner in range(n):
        t.pu()
        t.goto(points[inner])
        t.pd()
        t.goto(points[(inner+2)%n])

def outer_poly(points, n):
    """Draw only the edges of an n-gon defined by points"""
    t.pu()
    t.goto(points[-1])
    t.pd()
    for side in range(n):
        t.goto(points[side])

t = turtle.Turtle()
t.lt(90)
t.speed(0)
t.ht()

# n is the number of sides of the polygon it draws
# i is the number of iterations
# r is the starting radius of the polygon
n = 7
i = 10
r = 200

s = 2*cos(pi/n) - 1/cos(pi/n)

p = points(n, r)
outer_poly(p, n)
for _ in range(i):
    incomplete_poly(p, n)
    p = scale(rotate(p, pi/n), s)

ts = turtle.getscreen()
ts.getcanvas().postscript(file="7-intergon.eps")

turtle.done()