def dot_str(self, wrap=10, **kwargs):
        """Return dot string.

        Requires pydot.
        """
        from tulip.transys.export import graph2dot
        return graph2dot.graph2dot_str(self, wrap, **kwargs)
    def dot_str(self, wrap=10, **kwargs):
        """Return dot string.

        Requires pydot.
        """
        from tulip.transys.export import graph2dot
        return graph2dot.graph2dot_str(self, wrap, **kwargs)