Create Hidden Folder

        Create a hidden folder.  Raise exception if auto delete isn't True.

        @return: Created folder.

def createHiddenFolder(self) -> 'File':
        """ Create Hidden Folder

        Create a hidden folder.  Raise exception if auto delete isn't True.

        @return: Created folder.
        """

        if not self._autoDelete:
            raise Exception("Hidden folders can only be created within"
                            " an autoDelete directory")
        return tempfile.mkdtemp(dir=self._path, prefix=".")