code: def get_summary_str(self, sec2d_nt):
          
          data = self.get_summary_data(sec2d_nt)
          return "{M} GO IDs placed into {N} sections; {U} unplaced GO IDs".format(
              N=len(data['sections']), M=len(data['grouped']), U=len(data['ungrouped']))
docs: Get string describing counts of placed/unplaced GO IDs and count of sections.