Kindly explain how this code rrun

Question

def is_even(x):
if x == 0:
return True
else:
return is_odd(x-1)

def is_odd(x):
return not is_even(x)

print(is_odd(17))
print(is_even(23))

Answer 1

A number is even if and only if that number-1 is odd. The program works for positive integers only (including 0).