Create and return a default notes master part, including creating the
        new theme it requires.

def create_default(cls, package):
        """
        Create and return a default notes master part, including creating the
        new theme it requires.
        """
        notes_master_part = cls._new(package)
        theme_part = cls._new_theme_part(package)
        notes_master_part.relate_to(theme_part, RT.THEME)
        return notes_master_part