Get a GO DAG in a dot-language string for a single Group of user GOs.

def _get_dotgraphs(self, hdrgo, usrgos, pltargs, go2parentids):
        """Get a GO DAG in a dot-language string for a single Group of user GOs."""
        gosubdagplotnts = self._get_gosubdagplotnts(hdrgo, usrgos, pltargs, go2parentids)
        # Create DAG graphs as dot language strings. Loop through GoSubDagPlotNt list
        dotstrs = [obj.get_dotstr() for obj in gosubdagplotnts]
        return dotstrs