def METHOD_NAME(posterior):
    """Called at a grid point, the respective disrete solution is returned."""
    first_point = posterior.locations[0]
    np.testing.assert_allclose(posterior(first_point).mean, posterior[0].mean)
    np.testing.assert_allclose(posterior(first_point).cov, posterior[0].cov)
    final_point = posterior.locations[-1]
    np.testing.assert_allclose(posterior(final_point).mean, posterior[-1].mean)
    np.testing.assert_allclose(posterior(final_point).cov, posterior[-1].cov)
    mid_point = posterior.locations[4]
    np.testing.assert_allclose(posterior(mid_point).mean, posterior[4].mean)
    np.testing.assert_allclose(posterior(mid_point).cov, posterior[4].cov)