old_contents: from pymongo import MongoClient
  
  
  def main():
      client = MongoClient()
      db = client.cityhotspots
      db.drop_collection('dineroptions')
      diners_collection = db.diners
  
      doc = {}
      diner_options_collection = db.dineroptions
      doc['categories'] = diners_collection.distinct('category')
      doc['cuisines'] = diners_collection.distinct('cuisine')
      doc['districts'] = diners_collection.distinct('address.district')
      diner_options_collection.insert(doc)
  
  
  if __name__ == '__main__':
      main()
  
new_contents: from pymongo import MongoClient
  
  
  def main():
      client = MongoClient()
      db = client.cityhotspots
      db.drop_collection('dineroptions')
      diners_collection = db.diners
  
      doc = {}
      diner_options_collection = db.dineroptions
      doc['categories'] = diners_collection.distinct('category')
      doc['cuisines'] = diners_collection.distinct('cuisine')
      doc['districts'] = diners_collection.distinct('address.district')
  
      doc['max_price'] = list(diners_collection.aggregate([{
          "$group":
              {
                  "_id": None,
                  "max": {"$max": "$price_max"}
              }
      }]))[0]['max']
      doc['min_price'] = list(diners_collection.aggregate([{
          "$group":
              {
                  "_id": None,
                  "min": {"$min": "$price_min"}
              }
      }]))[0]['min']
      
      diner_options_collection.insert(doc)
  
  
  if __name__ == '__main__':
      main()
  
subject: Add min_price and max_price fields