How to use the graphviz._compat.text_type function in graphviz

format: The output format used for rendering (``'pdf'``, ``'png'``, etc.).
            renderer: The output renderer used for rendering (``'cairo'``, ``'gd'``, ...).
            formatter: The output formatter used for rendering (``'cairo'``, ``'gd'``, ...).
            quiet (bool): Suppress ``stderr`` output from the layout subprocess.
        Returns:
            Binary (encoded) stdout of the layout command.
        Raises:
            ValueError: If ``format``, ``renderer``, or ``formatter`` are not known.
            graphviz.RequiredArgumentError: If ``formatter`` is given but ``renderer`` is None.
            graphviz.ExecutableNotFound: If the Graphviz executable is not found.
            subprocess.CalledProcessError: If the exit status is non-zero.
        """
        if format is None:
            format = self._format

        data = text_type(self.source).encode(self._encoding)

        out = backend.pipe(self._engine, format, data,
                           renderer=renderer, formatter=formatter,
                           quiet=quiet)

        return out

Args:
            filename: Filename for saving the source (defaults to ``name`` + ``'.gv'``)
            directory: (Sub)directory for source saving and rendering.
        Returns:
            The (possibly relative) path of the saved source file.
        """
        if filename is not None:
            self.filename = filename
        if directory is not None:
            self.directory = directory

        filepath = self.filepath
        tools.mkdirs(filepath)

        data = text_type(self.source)

        log.debug('write %d bytes to %r', len(data), filepath)
        with io.open(filepath, 'w', encoding=self.encoding) as fd:
            fd.write(data)
            if not data.endswith(u'\n'):
                fd.write(u'\n')

        return filepath