code: def get_sections_2d_nts(self, sortby=None):
          
          sections_2d_nts = []
          for section_name, hdrgos_actual in self.get_sections_2d():
              hdrgo_nts = self.gosubdag.get_nts(hdrgos_actual, sortby=sortby)
              sections_2d_nts.append((section_name, hdrgo_nts))
          return sections_2d_nts
docs: Get high GO IDs that are actually used to group current set of GO IDs.