How to toggle a value in Python

Question

What is the most efficient way to toggle between 0 and 1?

Answer 1

Switching between -1 and +1 can be obtained by inline multiplication; used for calculation of pi the 'Leibniz' way (or similar):

sign = 1
result = 0
for i in range(100000):
    result += 1 / (2*i + 1) * sign
    sign *= -1
print("pi (estimate): ", result*4)