docs: def check_suspension(user_twitter_id_list):
      """
      Looks up a list of user ids and checks whether they are currently suspended.
  
      Input: - user_twitter_id_list: A python list of Twitter user ids in integer format to be looked-up.
  
      Outputs: - suspended_user_twitter_id_list: A python list of suspended Twitter user ids in integer format.
               - non_suspended_user_twitter_id_list: A python list of non suspended Twitter user ids in integer format.
               - unknown_status_user_twitter_id_list: A python list of unknown status Twitter user ids in integer format.
      """
      ####################################################################################################################
      # Log into my application.
      ####################################################################################################################
      twitter = login()
  
      ####################################################################################################################
      # Lookup users
      ####################################################################################################################
      # Initialize look-up lists
      suspended_user_twitter_id_list = list()
      non_suspended_user_twitter_id_list = list()
      unknown_status_user_twitter_id_list = list()
  
      append_suspended_twitter_user = suspended_user_twitter_id_list.append
      append_non_suspended_twitter_user = non_suspended_user_twitter_id_list.append
      extend_unknown_status_twitter_user = unknown_status_user_twitter_id_list.extend
  
      # Split twitter user id list into sub-lists of length 100 (This is the Twitter API function limit).
      user_lookup_counter = 0
      user_lookup_time_window_start = time.perf_counter()
      for hundred_length_sub_list in chunks(list(user_twitter_id_list), 100):
          # Make safe twitter request.
          try:
              api_result, user_lookup_counter, user_lookup_time_window_start\
                  = safe_twitter_request_handler(twitter_api_func=twitter.lookup_user,
                                                 call_rate_limit=60,
                                                 call_counter=user_lookup_counter,
                                                 time_window_start=user_lookup_time_window_start,
                                                 max_retries=10,
                                                 wait_period=2,
                                                 parameters=hundred_length_sub_list)
              # If the call is succesful, turn hundred sub-list to a set for faster search.
              hundred_length_sub_list = set(hundred_length_sub_list)
  
              # Check who is suspended and who is not.
              for hydrated_user_object in api_result:
                  hydrated_twitter_user_id = hydrated_user_object["id"]
  
                  if hydrated_twitter_user_id in hundred_length_sub_list:
                      append_non_suspended_twitter_user(hydrated_twitter_user_id)
                  else:
                      append_suspended_twitter_user(hydrated_twitter_user_id)
          except twython.TwythonError:
              # If the call is unsuccesful, we do not know about the status of the users.
              extend_unknown_status_twitter_user(hundred_length_sub_list)
          except URLError:
              # If the call is unsuccesful, we do not know about the status of the users.
              extend_unknown_status_twitter_user(hundred_length_sub_list)
          except BadStatusLine:
              # If the call is unsuccesful, we do not know about the status of the users.
              extend_unknown_status_twitter_user(hundred_length_sub_list)
  
      return suspended_user_twitter_id_list, non_suspended_user_twitter_id_list, unknown_status_user_twitter_id_list