code: def rangize_supplement(spans,lngth):
      '''
          spans = [(0, 3), (4, 7), (8, 10), (11, 12), (13, 16), (17, 20)]
          rangize_supplement(spans,24)
          
      '''
      rslt = []
      si = 0
      ei = spans[0][0]
      if(si == ei):
          pass
      else:
          rslt.append((si,ei))
      prev_ei = spans[0][1]
      for i in range(1,spans.__len__()):
          si = prev_ei
          ei = spans[i][0]
          rslt.append((si,ei))
          prev_ei = spans[i][1]
      if(prev_ei < lngth):
          rslt.append((prev_ei,lngth))
      else:
          rslt.append((prev_ei,lngth+1))
      return(rsltf rangize_supplement(spans,lngth):
      '''
          spans = [(0, 3), (4, 7), (8, 10), (11, 12), (13, 16), (17, 20)]
          rangize_supplement(spans,24)
          
      '''
      rslt = []
      si = 0
      ei = spans[0][0]
      if(si == ei):
          pass
      else:
          rslt.append((si,ei))
      prev_ei = spans[0][1]
      for i in range(1,spans.__len__()):
          si = prev_ei
          ei = spans[i][0]
          rslt.append((si,ei))
          prev_ei = spans[i][1]
      if(prev_ei < lngth):
          rslt.append((prev_ei,lngth))
      else:
          rslt.append((prev_ei,lngth+1))
      return(rslt)
docs: spans = [(0, 3), (4, 7), (8, 10), (11, 12), (13, 16), (17, 20)]
          rangize_supplement(spans,24)