code: def _get_n_columns(tag):
      """Return the the number of columns to use in tests."""
      n_columns_list = []
      if tag in ["univariate", "both"]:
          n_columns_list = [1, 2]
      elif tag == "multivariate":
          n_columns_list = [2]
      else:
          raise ValueError(f"Unexpected tag {tag} in _get_n_columns.")
      return n_columns_list
  
file_path: sktime/sktime/utils/_testing/forecasting.py
imports: import numpy
  import pandas
  from sktime.forecasting.base import ForecastingHorizon
  from sktime.utils._testing.series import _make_series
  from sktime.utils.validation.forecasting import check_fh
label_desc: Use image node_id 1 for calling a global function with example usage: _get_n_columns(tag) and returns: n_columns_list