code: def test__get_missing_timestamps(timeseries_dataframe):
      """Test utility function for identifying the missing timestamps."""
      from random import sample
  
      timeseries_dataframe.index.freq = None
      timestamps_to_drop = sample(
          timeseries_dataframe.index.tolist(), 3
      )
      df = timeseries_dataframe.drop(index=timestamps_to_drop)
      missing_timestamps = _get_missing_timestamps(df, "1H")
      assert set(missing_timestamps.index) == set(timestamps_to_drop)
  
imports: from random import randint
  import pandas
  import pytest
  from janitor.timeseries import _get_missing_timestamps, fill_missing_timestamps
label_desc: Use image node_id 3 for calling a global function with example usage: test__get_missing_timestamps(timeseries_dataframe) without return types