Add alt GO IDs to go2obj subset, if requested and relevant.

def _add_goterms(self, go2obj_user, goid):
        """Add alt GO IDs to go2obj subset, if requested and relevant."""
        goterm = self.go2obj_orig[goid]
        if goid != goterm.id and goterm.id in go2obj_user and goid not in go2obj_user:
            go2obj_user[goid] = goterm