def _view(self, filepath, format):
        """Start the right viewer based on file format and platform."""
        methods = [
            (format, backend.PLATFORM) % '_view_%s_%s',
            '_view_%s' % backend.PLATFORM,
        ]
        for name in methods:
            method = getattr(self, name, None)
            if method is not None:
                method(filepath)
                break
        else:
            raise RuntimeError('%r has no built-in viewer support for %r '
                'on %r platform' % (self.__class__, format, backend.PLATFORM))
dataset/ETHPy150Open xflr6/graphviz/graphviz/files.py/File._view/swapped operands of `%`