[Python] ModExponentiation code snippet

ModExponentiation code snippet:

def ModExponentiation(b, e, m):
  """
  Modular exponentiation algorithm of time complexity = O(log(e)).

  Args:
    b: An integer representing the base.
    e: An integer representing the exponent.
    m: An integer representing modulus.

  Returns:
    An integer c = b^e (mod m).
  """
  if e == 0:
    return 1
  y = b
  output = 1
  while e > 0:
    if e & 1 == 1:
      output = (output * y) % m
    y = (y * y) % m
    e >>= 1
  return output