如何用python求圆周率？

import math

import time

scale = 10

print("执行开始")

t=time.process_time()

for i in range(scale+1):

a,b = '**'*i,'|..'*(scale-1)

c = (i/scale)*100

π = 4*(4*math.atan(1/5)-math.atan(1/239))

print("%{:3}[{}->{}".format(a,b,c))

time.sleep(0.1)

print(π)

print("{:.2f}s".format(t))

print("执行结束")