Why in the world does running this program cause me to have to exit Pyscripter as a result of it being stuck in a debugging action?

Question

import math def my_sqrt(a): x = a + 2 while True: #print (x) y = (x+a/x)/2.0 if y == x: break x = y return x

def test_sqrt(z): def grid(): print ("a =", z,&