code: def test_get_timestamp_ceil():
      """Tests `get_timestamp_ceil`."""
      assert get_timestamp_ceil("2023-01-31", "M") == pd.to_datetime(
          "2023-01-31"
      )
      assert get_timestamp_ceil("2023-01-19", "M") == pd.to_datetime(
          "2023-01-31"
      )
      assert get_timestamp_ceil(
          "2023-01-18", "W-MON"
      ) == pd.to_datetime("2023-01-23")
      assert get_timestamp_ceil(
          "2023-01-23", "W-MON"
      ) == pd.to_datetime("2023-01-23")
      assert get_timestamp_ceil("2023-01-23", "D") == pd.to_datetime(
          "2023-01-23"
      )
      assert get_timestamp_ceil(
          "2023-01-22 20:15", "D"
      ) == pd.to_datetime("2023-01-23")
      assert get_timestamp_ceil("2023-01-23", "B") == pd.to_datetime(
          "2023-01-23"
      )
      assert get_timestamp_ceil(
          "2023-01-21 10:15", "B"
      ) == pd.to_datetime("2023-01-23")
      assert get_timestamp_ceil(
          "2023-01-23 10:00:00", "H"
      ) == pd.to_datetime("2023-01-23 10:00:00")
      assert get_timestamp_ceil(
          "2023-01-23 09:15:40", "H"
      ) == pd.to_datetime("2023-01-23 10:00:00")
      assert get_timestamp_ceil(
          "2023-01-23 10:15:00", "T"
      ) == pd.to_datetime("2023-01-23 10:15:00")
      assert get_timestamp_ceil(
          "2023-01-23 10:14:40", "T"
      ) == pd.to_datetime("2023-01-23 10:15:00")
  
imports: import itertools
  import numpy
  import pandas
  import pytest
  from testfixtures import LogCapture
  from greykite.common.constants import ANOMALY_COL
  from greykite.common.constants import END_TIME_COL
  from greykite.common.constants import LOGGER_NAME
  from greykite.common.constants import START_TIME_COL
  from greykite.common.constants import TIME_COL
  from greykite.common.constants import TimeFeaturesEnum
  from greykite.common.testing_utils import assert_equal
  from greykite.detection.detector.ad_utils import add_new_params_to_records
  from greykite.detection.detector.ad_utils import get_anomaly_df
  from greykite.detection.detector.ad_utils import get_anomaly_df_from_outliers
  from greykite.detection.detector.ad_utils import get_canonical_anomaly_df
  from greykite.detection.detector.ad_utils import get_timestamp_ceil
  from greykite.detection.detector.ad_utils import get_timestamp_floor
  from greykite.detection.detector.ad_utils import optimize_df_with_constraints
  from greykite.detection.detector.ad_utils import partial_return
  from greykite.detection.detector.ad_utils import validate_volatility_features
  from greykite.detection.detector.ad_utils import vertical_concat_dfs
label_desc: Use image node_id 9 for calling a global function with example usage: test_get_timestamp_ceil() without return types