def METHOD_NAME():
    exponent = ExponentTransformer()
    pipe = Pipeline()
    pipe = pipe.add_step(exponent, "exponent", {"X": "X"})
    expected_message = (
        "You try to add a step with a name 'exponent' to the pipeline "
        "that already exists. Try to use an other name."
    )
    pipe = pipe.add_step(exponent, "exponent", {"X": "X"})
    with pytest.raises(ValueError, match=expected_message):
        pipe.fit(MagicMock(), MagicMock())