def _render_content(self, content, **settings):
        """
        Render the tree widget.
        """
        if isinstance(content, dict):
            return self._render_content_dict(content, 0, [], **settings)
        elif isinstance(content, list):
            return self._render_content_list(content, 0, [], **settings)
        else:
            raise Exception("Received invalid data tree for rendering.")
Render the tree widget.