code: def encode_username_password(
      username: Union[str, bytes], password: Union[str, bytes]
  ) -> bytes:
      
      if isinstance(username, unicode_type):
          username = unicodedata.normalize("NFC", username)
      if isinstance(password, unicode_type):
          password = unicodedata.normalize("NFC", password)
      return utf8(username) + b":" + utf8(password)
docs: Encodes a username/password pair in the format used by HTTP auth.
  
      The return value is a byte string in the form ``username:password``.
  
      .. versionadded:: 5.1