code: def safe_str_cmp(a, b):
      
      if _builtin_safe_str_cmp is not None:
          return _builtin_safe_str_cmp(a, b)
      if len(a) != len(b):
          return False
      rv = 0
      if isinstance(a, bytes) and isinstance(b, bytes) and not PY2:
          for x, y in izip(a, b):
              rv |= x ^ y
      else:
          for x, y in izip(a, b):
              rv |= ord(x) ^ ord(y)
      return rv == 0
docs: This function compares strings in somewhat constant time.  This
      requires that the length of at least one string is known in advance.
  
      Returns `True` if the two strings are equal or `False` if they are not.
  
      .. versionadded:: 0.7