old_contents: #!/usr/bin/python3.6
  import json
  import logging
  from lib import rank
  from lib import webutil
  
  def average(event, context):
      ranking_average = {
          'rankings': rank.average_individual()
      }
      return webutil.respond_success_json(ranking_average)
  
new_contents: #!/usr/bin/python3.6
  import json
  import logging
  from lib import rank
  from lib import webutil
  
  def average(event, context):
      ranking_average = {
          'rankings': rank.average_individual()
      }
      return webutil.respond_success_json(json.dumps(ranking_average))
  
subject: fix ranking api for new json serialization