> I also want "detect if there are any surrogates".

Could you please open a separated issue for this function/method?

I believe that it's very different than other proposed functions/methods.

It was proposed before to add methods like "is_ascii()" but the request was rejected because other Python implementations don't implement Unicode using the PEP 393 and so the method would be less efficient than expected, depending on the implementation of Python.

Well, I don't know if we should add methods relying on the PEP 393 or not. It's probably better to discuss such "political" question on python-dev.