def setup(self):
        """Setup."""

        extensions = []
        extension_configs = {}
        for item in self.config['markdown_extensions']:
            if isinstance(item, str):
                extensions.append(item)
            else:
                k, v = list(item.items())[0]
                extensions.append(k)
                if v is not None:
                    extension_configs[k] = v
        self.markdown = markdown.Markdown(extensions=extensions, extension_configs=extension_configs)