def METHOD_NAME(runner):
    """Test that using a runner works with a 2D learner, even when the
    learned function outputs a 1-vector. This tests against the regression
    flagged in https://github.com/python-adaptive/adaptive/issues/81.
    """
    def f(x):
        return [0]
    runner(Learner2D(f, ((-1, 1), (-1, 1))), npoints_goal=10)