Get function for sorting GO terms in a list of namedtuples.

def _get_sortgo(self):
        """Get function for sorting GO terms in a list of namedtuples."""
        if 'sortgo' in self.datobj.kws:
            return self.datobj.kws['sortgo']
        return self.datobj.grprdflt.gosubdag.prt_attr['sort'] + "\n"