docs: def read_user_documents_generator(user_twitter_id_list, client, mongo_database_name, mongo_collection_name):
      """
      Stores Twitter list objects that a Twitter user is a member of in different mongo collections.
  
      Inputs: - user_twitter_id_list: A python list of Twitter user ids.
              - client: A pymongo MongoClient object.
              - mongo_database_name: The name of a Mongo database as a string.
              - mongo_collection_name: The name of the mongo collection as a string.
  
      Yields: - user_twitter_id: A Twitter user id.
              - twitter_list_gen: A python generator that yields Twitter lists in dictionary (json) format.
      """
      mongo_database = client[mongo_database_name]
      mongo_collection = mongo_database[mongo_collection_name]
  
      # cursor = mongo_collection.find({"_id": {"$in": [int(user_twitter_id) for user_twitter_id in user_twitter_id_list]}})
      cursor = mongo_collection.find()
  
      user_twitter_id_list = [int(user_twitter_id) for user_twitter_id in user_twitter_id_list]
      user_twitter_id_list = set(user_twitter_id_list)
  
      for documents in cursor:
          if documents["_id"] in user_twitter_id_list:
              yield documents["_id"], documents