code: def compare(string1, string2):
      
      if len(string1) != len(string2):
          return False
      result = True
      for c1, c2 in izip(string1, string2):
          result &= c1 == c2
      return result
docs: Compare two strings while protecting against timing attacks
  
      :param str string1: the first string
      :param str string2: the second string
  
      :returns: True if the strings are equal, False if not
      :rtype: :obj:`bool`