code: def prt_hier_down(self, goid, prt=sys.stdout):
          
          wrhiercfg = self._get_wrhiercfg()
          obj = WrHierPrt(self.gosubdag.go2obj, self.gosubdag.go2nt, wrhiercfg, prt)
          obj.prt_hier_rec(goid)
          return obj.items_list
docs: Write hierarchy for all GO IDs below GO ID in arg, goid.