multiple turtle make star

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

# turtle.delay(50)

def cart2pol(x, y):
    r = sqrt(x**2 + y**2)
    phi = atan(y, x)
    return (r, phi)


def pol2cart(r, phi, radian_scale_factor=1):
    x = r * cos(phi*radian_scale_factor)
    y = r * sin(phi*radian_scale_factor)
    return (x, y)

def star(centerx, centery, internal_radius, external_radius,  ray_count = 24, radian_scale_factor=1):
    vertex_count = ray_count * 2 
    VERTEX_POLAR = [[external_radius if (i % 2 == 0) else internal_radius, \
            (i * 2 * pi/vertex_count)]  for i in range(-vertex_count//2,vertex_count//2)]
    VERTEX_CART = [pol2cart(*v, radian_scale_factor=radian_scale_factor)  for v in VERTEX_POLAR]
    # move center of star to ( centerx, centery )
    center = (centerx, centery)
    VERTEX_CART = [[sum(i) for i in zip(v, center)] for v in VERTEX_CART]
    return VERTEX_CART

#for step in range(vlen):
def move_other(): # the function to move the second turtle
    global step, vlen, tlist
    if step < vlen:
        for ct in tlist:
            VERTEX_CART=ct['v']
            ct['t'].goto(*VERTEX_CART[step])
            if not ct['t'].isdown(): ct['t'].pd()
        screen.ontimer(move_other,150) # which sets itself up to be called again
        step += 1
        screen.update()
    else:
        for ct in (tlist[-1],):
            VERTEX_CART=ct['v']
            ct['t'].goto(*VERTEX_CART[0])
            if not ct['t'].isdown(): ct['t'].pu()
        step = 0 
        for ct in tlist[0:-1]:
            ct['t'].hideturtle()
        screen.update()
        print("circle done")


  
min_rad=20
max_rad=500
tlist = []
steps=32
VERTEX_CART_STEPS = 16
turtle.colormode(255)
screen = turtle.Screen()
screen.tracer(0,0)

for i in range(steps):
    ct=dict()
    ct['t']=turtle.Turtle()
    cur_min_rad = min_rad+(steps-i)*(max_rad-min_rad)/steps
    cur_max_rad = min_rad+(steps-i+1)*(max_rad-min_rad)/steps
    VERTEX_CART=star(0, 0, cur_min_rad, cur_max_rad  ,  ray_count = VERTEX_CART_STEPS, radian_scale_factor= (i+1) * 1/steps)
    ct['v']=VERTEX_CART
    ct['t'].pencolor(int(255 * (steps-i)/ steps), 100, int(255 * i/ steps) )
    ct['t'].speed(1)
    ct['t'].shape('circle')
    ct['t'].shapesize(0.25)
    ct['t'].pu()
    #ct['t'].hideturtle()
    tlist.append(ct)
    
vlen = len(VERTEX_CART)
step = 0 

move_other()
ct['t'].goto(*VERTEX_CART[0])


screen.mainloop()