user_pin and so_pin in Token.open() are documented as bytes, instead they are str

In the docstring of the Token open function user_pin and so_pin are documented as bytes, but the code assumes they are strings:

      elif user_pin is not None:
            pin = user_pin.encode('utf-8')
            c_user_type = user_type if user_type is not None else CKU_USER
        elif so_pin is not None:
            pin = so_pin.encode('utf-8')
            c_user_type = CKU_SO

This causes pycharm (and other type checking tools) to complain

Start at the Token.open() docstring and compare the documented types for user_pin and so_pin with the encode calls shown in the issue. Update the parameter documentation to match the string values accepted by the implementation, then run the relevant existing tests or documentation checks; done means type-checking tools no longer report this mismatch.