def convert_epub_css_files(app: Sphinx, config: Config) -> None: """This converts string styled epub_css_files to tuple styled one.""" epub_css_files = [] # type: List[Tuple[str, Dict]] for entry in config.epub_css_files: if isinstance(entry, str): epub_css_files.append((entry, {})) else: try: filename, attrs = entry epub_css_files.append((filename, attrs)) except Exception: logger.warning(__('invalid css_file: %r, ignored'), entry) continue config.epub_css_files = epub_css_files # type: ignore