code: def test_missing_timestamps_during_aggregation(
      params, hourly_data_with_reg
  ):
      model = MultistageForecastEstimator(**params)
      model.time_col_ = cst.TIME_COL
      model.value_col_ = cst.VALUE_COL
      model._initialize()
      df = model._add_agg_freq_cols(df=hourly_data_with_reg)
      df = df.iloc[
          1:-1
      ]  # both the beginning period and the end period are incomplete.
      # Removes one timestamp in the middle.
      df = pd.concat([df.iloc[:50], df.iloc[51:]], axis=0).reset_index(
          drop=True
      )
      with LogCapture(cst.LOGGER_NAME) as log_capture:
          model._drop_incomplete_agg_and_aggregate_values(
              df=df,
              agg_freq="D",
              agg_func=np.mean,
              num_points_per_agg_freq=24,
              drop_incomplete=True,
              index=0,
          )
          log_capture.check_present(
              (
                  cst.LOGGER_NAME,
                  "WARNING",
                  "There are missing timestamps in `df` when performing aggregation with "
                  "frequency D. These points are              y\n"
                  "ts            \n"
                  "2018-01-03  23. This may cause the aggregated values to be biased.",
              )
          )
  
imports: import datetime
  import numpy
  import pandas
  import pytest
  from testfixtures import LogCapture
  import greykite.common.constants
  from greykite.common.testing_utils import generate_df_for_tests
  from greykite.sklearn.estimator.lag_based_estimator import LagBasedEstimator
  from greykite.sklearn.estimator.multistage_forecast_estimator import MultistageForecastEstimator
  from greykite.sklearn.estimator.multistage_forecast_estimator import MultistageForecastModelConfig
  from greykite.sklearn.estimator.simple_silverkite_estimator import SimpleSilverkiteEstimator
  from greykite.sklearn.uncertainty.uncertainty_methods import UncertaintyMethodEnum
label_desc: Use image node_id 21 for calling a global function with example usage: test_missing_timestamps_during_aggregation(params, hourly_data_with_reg) without return types