docs: def compute_auth_key(userid, password):
      """
      Compute the authentication key for freedns.afraid.org.
  
      This is the SHA1 hash of the string b'userid|password'.
  
      :param userid: ascii username
      :param password: ascii password
      :return: ascii authentication key (SHA1 at this point)
      """
      import sys
      if sys.version_info >= (3, 0):
          return hashlib.sha1(b"|".join((userid.encode("ascii"),  # noqa: S303
                                         password.encode("ascii")))).hexdigest()
      return hashlib.sha1("|".join((userid, password))).hexdigest()