def save_dot(self, file_name='graph.dot'):
        """Save the graph in a graphviz dot file.

        Parameters
        ----------
        file_name : Optional[str]
            The name of the file to save the graph dot string to.
        """
        s = self.get_string()
        with open(file_name, 'wt') as fh:
            fh.write(s)
Save the graph in a graphviz dot file.

        Parameters
        ----------
        file_name : Optional[str]
            The name of the file to save the graph dot string to.