def METHOD_NAME(test_case):
    with test_case.assertRaises(Exception) as context:
        x = flow.randn(2)
        x.requires_grad = True
        m = flow.nn.Softshrink(-0.1)
        y = m(x)
    test_case.assertTrue(
        "alpha must be greater or equal to 0, but found to be -0.1."
        in str(context.exception)
    )