code: def test_get_similar_lag():
      """Tests get_similar_lag"""
      # Daily data
      assert get_similar_lag(freq_in_days=1) == 7
      # 2 days frequency
      assert get_similar_lag(freq_in_days=2) == 4
      # Weekly data
      assert get_similar_lag(freq_in_days=7) is None
      # Monthly data
      assert get_similar_lag(freq_in_days=30) is None
      # Hourly data
      assert get_similar_lag(freq_in_days=1 / 24) == 24 * 7
      # Two hour frequency
      assert get_similar_lag(freq_in_days=1 / 12) == 12 * 7
  
file_path: greykite/greykite/tests/algo/forecast/silverkite/test_forecast_silverkite_helper.py
imports: import datetime
  import pandas
  import pytest
  from greykite.algo.forecast.silverkite.forecast_silverkite_helper import get_default_changepoints_dict
  from greykite.algo.forecast.silverkite.forecast_silverkite_helper import get_fourier_feature_col_names
  from greykite.algo.forecast.silverkite.forecast_silverkite_helper import get_silverkite_uncertainty_dict
  from greykite.algo.forecast.silverkite.forecast_silverkite_helper import get_similar_lag
  from greykite.common.features.timeseries_features import fourier_series_multi_fcn
  from greykite.common.python_utils import assert_equal
  from greykite.common.testing_utils import generate_df_for_tests
label_desc: Use image node_id 6 for calling a global function with example usage: test_get_similar_lag() without return types