Calculate the fixed point of cosine in Python

python-cosine-fixedpoint.py

import math

tolerance = 0.00000000000000000001

def tolerance_equals(a, b):
  return ((a - b) * (a - b)) < tolerance

def recursive_cosine_fixedpoint(a):
  if tolerance_equals(a, math.cos(a)):
    return a
  return recursive_cosine_fixedpoint(math.cos(a))


print("The fixed point of cosine is {}".format(recursive_cosine_fixedpoint(1)))
# The fixed point of cosine is 0.7390851331706995