code: def get_go2obj_unique(go2obj):
      
      # Find the unique GO Terms that are represented for each GO in go2obj
      goid2gokeys = cx.defaultdict(set)
      for goid, goobj in go2obj.items():
          goid2gokeys[goobj.id].add(goid)
      go_unique = set()
      for goid, gos_seen in goid2gokeys.items():
          # Return main GO ID, if it is present in the go2obj keys
          if goid in gos_seen:
              go_unique.add(goid)
          # Otherwise return an alternate GO ID
          else:
              go_unique.add(next(iter(gos_seen)))
      return go_unique
docs: If GO keys point to the same GOTerm, return new go2obj w/no duplicates.