code: def test_init_TypeError_when_fun_predictors_is_not_a_Callable():
      """
      Test TypeError is raised when fun_predictors is not a Callable.
      """
      fun_predictors = "not_valid_type"
      err_msg = re.escape(
          f"Argument `fun_predictors` must be a Callable. Got {type(fun_predictors)}."
      )
      with pytest.raises(TypeError, match=err_msg):
          ForecasterAutoregMultiSeriesCustom(
              regressor=LinearRegression(),
              fun_predictors="not_valid_type",
              window_size=5,
          )
  
file_path: skforecast/skforecast/ForecasterAutoregMultiSeriesCustom/tests/test_init.py
imports: import re
  import pytest
  from skforecast.ForecasterAutoregMultiSeriesCustom import ForecasterAutoregMultiSeriesCustom
  from sklearn.linear_model import LinearRegression
label_desc: Use image node_id 3 for calling a global function with example usage: test_init_TypeError_when_fun_predictors_is_not_a_Callable() without return types