code: def test_listlabel_mixed_label_error():
      with pytest.raises(TypeError) as type_error:
          df = pd.DataFrame(
              {"a": [1], "c": [-0.5], "p": [0.1], "b": [2], "x": [1]}
          )
          conv = DFtoVW(
              df=df,
              label=[
                  ContextualbanditLabel("a", "c", "p"),
                  MultiLabel("b"),
              ],
              features=Feature("x"),
          )
      expected = "The list passed in 'label' has mixed label types."
      assert expected == str(type_error.value)
  
imports: import pytest
  import pandas
  from vowpalwabbit.dftovw import ContextualbanditLabel, DFtoVW, Feature, MulticlassLabel, MultiLabel, Namespace, SimpleLabel
label_desc: Use image node_id 34 for calling a global function with example usage: test_listlabel_mixed_label_error() without return types