Get 2-D list: 1st level is sections and 2nd level is grouped and sorted namedtuples.

def get_sorted_nts_keep_section(self, hdrgo_prt):
        """Get 2-D list: 1st level is sections and 2nd level is grouped and sorted namedtuples."""
        section_nts = []
        # print("SSSS SorterNts:get_sorted_nts_keep_section(hdrgo_prt={})".format(hdrgo_prt))
        hdrgos_actual = self.sortgos.grprobj.get_hdrgos()
        hdrgos_secs = set()
        hdrgo_sort = False if self.section_sortby is False else True
        secname_dflt = self.sortgos.grprobj.hdrobj.secdflt
        for section_name, section_hdrgos_all in self.sections:
            #section_hdrgos_act = set(section_hdrgos_all).intersection(hdrgos_actual)
            section_hdrgos_act = [h for h in section_hdrgos_all if h in hdrgos_actual]
            hdrgos_secs |= set(section_hdrgos_act)
            nts_section = self.sortgos.get_nts_sorted(hdrgo_prt, section_hdrgos_act, hdrgo_sort)
            if nts_section:
                nts_section = self._get_sorted_section(nts_section)
                section_nts.append((section_name, nts_section))
        remaining_hdrgos = hdrgos_actual.difference(hdrgos_secs)
        # Add GO group headers not yet used under new section, Misc.
        if remaining_hdrgos:
            nts_section = self.sortgos.get_nts_sorted(hdrgo_prt, remaining_hdrgos, hdrgo_sort)
            if nts_section:
                nts_section = self._get_sorted_section(nts_section)
                section_nts.append((secname_dflt, nts_section))
        return section_nts