code: def test_check_target_col():
      # Create sample DataFrames for testing
      df_binary = pd.DataFrame({"target": [0, 1, 0, 1, 1]})
      df_multi_class = pd.DataFrame(
          {
              "class1": [1, 0, 0],
              "class2": [0, 1, 0],
              "class3": [0, 0, 1],
          }
      )
      df_regression = pd.DataFrame(
          {"target": [1.5, 2.3, 3.1, 4.6, 5.9]}
      )
  
      assert _check_col("target", df_binary) == "binary"
      assert (
          _check_col(["class1", "class2", "class3"], df_multi_class)
          == "multi-class"
      )
      assert _check_col("target", df_regression) == "regression"
  
imports: import pandas
  import numpy
  import pytest
  from pdpbox.utils import FeatureInfo, _to_rgba, _check_col, _check_dataset, _make_list, _check_model, _check_classes, _check_memory_limit, _check_frac_to_plot, _calc_n_jobs, _get_string, _expand_params_for_interact, _calc_preds, _check_cluster_params, _check_plot_engine, _check_pdp_interact_plot_type
label_desc: Use image node_id 2 for calling a global function with example usage: test_check_target_col() without return types