docstr: Checks that predicted order_by values are timestamps 
docstr_tok: ["Checks","that","predicted","order_by","values","are","timestamps"]
code: def test_11_output_date_format(self):
      """Checks that predicted order_by values are timestamps"""
      np.random.seed(0)
      data = pd.read_csv("tests/data/arrivals.csv")
      data = data[data["Country"] == "US"]
      order_by = "T"
      train_df, test_df = self.split_arrivals(data, grouped=False)
      predictor = predictor_from_problem(
          train_df,
          ProblemDefinition.from_dict(
              {
                  "target": "Traffic",
                  "time_aim": 30,
                  "timeseries_settings": {
                      "order_by": order_by,
                      "window": 5,
                      "horizon": 2,
                  },
              }
          ),
      )
      predictor.learn(train_df)
      preds = predictor.predict(
          test_df.iloc[[-1]], args={"time_format": "infer"}
      )
      self.assertTrue(
          preds[f"order_{order_by}"].iloc[-1]
          in (["2012-06", "2012-09"], ["2012-07", "2012-10"])
      )
  
      preds = predictor.predict(
          test_df.iloc[[-1]], args={"time_format": "%Y"}
      )
      self.assertEqual(
          preds[f"order_{order_by}"].iloc[-1], ["2012", "2012"]
      )
  
imports: import random
  from datetime import datetime
  from datetime import timedelta
  import unittest
  import numpy
  import pandas
  from typing import List
  from scipy import signal
  from sklearn.metrics import r2_score
  from lightwood.api.types import ProblemDefinition
  from tests.utils.timing import train_and_check_time_aim
  from sktime.forecasting.base import ForecastingHorizon
  from sktime.forecasting.statsforecast import StatsForecastAutoARIMA
  from dataprep_ml.splitters import stratify
  from lightwood.api.high_level import json_ai_from_problem, code_from_json_ai, predictor_from_code, predictor_from_problem, predictor_from_json_ai
  from lightwood.mixer.sktime import SkTime
label_desc: Use image node_id 15 for calling the TestTimeseries obj's underlying member method code with example usage: obj.test_11_output_date_format() without return types