code: def simplify(geoids):
      
  
      from collections import defaultdict
  
      aggregated = defaultdict(set)
  
      d = {}
  
      for g in geoids:
  
          if not bool(g):
              continue
  
          av = g.allval()
  
          d[av] = None
  
          aggregated[av].add(g)
  
      compiled = set()
  
      for k, v in aggregated.items():
          if len(v) >= 5:
              compiled.add(k)
              compiled.add(k.promote())
          else:
              compiled |= v
  
      return compiled
docs: Given a list of geoids, reduce it to a simpler set. If there are five or more geoids at one summary level
      convert them to a single geoid at the higher level.
  
      :param geoids:
      :return: