code: def no_duplicates_sections2d(sections2d, prt=None):
      
      no_dups = True
      ctr = cx.Counter()
      for _, hdrgos in sections2d:
          for goid in hdrgos:
              ctr[goid] += 1
      for goid, cnt in ctr.most_common():
          if cnt == 1:
              break
          no_dups = False
          if prt is not None:
              prt.write("**SECTIONS WARNING FOUND: {N:3} {GO}\n".format(N=cnt, GO=goid))
      return no_dups
docs: Check for duplicate header GO IDs in the 2-D sections variable.