code: def constant_time_cmp(a, b):
      '''Compare two strings using constant time.'''
      result = True
      for x, y in zip(a, b):
          result &= (x == y)
      return resulf constant_time_cmp(a, b):
      '''Compare two strings using constant time.'''
      result = True
      for x, y in zip(a, b):
          result &= (x == y)
      return result
docs: Compare two strings using constant time.