def _write_template(self, data: T.Dict[str, T.Any], file_id: str, template_name: T.Optional[str] = None) -> None:
        ''' Render the template mustache files and write the result '''
        template_dir = Path(__file__).resolve().parent / 'templates'
        template_name = template_name or file_id
        template_name = f'{template_name}.mustache'
        template_file = template_dir / template_name

        # Import here, so that other generators don't also depend on it
        import chevron
        result = chevron.render(
            template=template_file.read_text(encoding='utf-8'),
            data=data,
            partials_path=template_dir.as_posix(),
            warn=True,
        )

        self._write_file(result, file_id)
 Render the template mustache files and write the result 
docs/refman/generatormd.py