code: def get_depth2goobjs(go2obj, max_depth=2):
          
          depth2goobjs = {d:list() for d in range(max_depth+1)}
          goid_seen = set()
          for _, goobj in sorted(go2obj.items(), key=lambda t: t[1].depth):
              # Save depth-00, depth-01, depth-02
              if goobj.depth > max_depth:
                  break
              goid = goobj.id
              if not goobj.is_obsolete and goid not in goid_seen:
                  depth2goobjs[goobj.depth].append(goobj)
                  goid_seen.add(goid)
          return depth2goobjs
docs: Init depth2goobjs using list sorted by depth, get level-00/01 GO terms.