Plot a GO DAG for the upper portion of a single Group of user GOs.

def _get_gos_upper(self, ntpltgo1, max_upper, go2parentids):
        """Plot a GO DAG for the upper portion of a single Group of user GOs."""
        # Get GO IDs which are in the hdrgo path
        goids_possible = ntpltgo1.gosubdag.go2obj.keys()
        # Get upper GO IDs which have the most descendants
        return self._get_gosrcs_upper(goids_possible, max_upper, go2parentids)