def dot(self):
        """
        Return a buffer that represents something dot(1) can render.
        """
        buff = "digraph graphname {"
        for fro in self.edges:
            for to in self.edges[fro]:
                buff += "%s -> %s;" % (fro, to)
        buff += "}"
        return buff
Return a buffer that represents something dot(1) can render.