def METHOD_NAME():
    grid = RasterModelGrid((7, 7))
    z = np.array(
        [
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            26.0,
            0.0,
            30.0,
            32.0,
            34.0,
            -9999.0,
            -9999.0,
            28.0,
            1.0,
            25.0,
            28.0,
            32.0,
            -9999.0,
            -9999.0,
            30.0,
            3.0,
            3.0,
            11.0,
            34.0,
            -9999.0,
            -9999.0,
            32.0,
            11.0,
            25.0,
            18.0,
            38.0,
            -9999.0,
            -9999.0,
            34.0,
            32.0,
            34.0,
            36.0,
            40.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
            -9999.0,
        ]
    )
    grid.at_node["topographic__elevation"] = z
    imposed_outlet = 2
    grid.set_watershed_boundary_condition_outlet_id(
        imposed_outlet, z, nodata_value=-9999.0
    )
    fr = FlowAccumulator(grid, flow_director="D8")
    fr.run_one_step()
    test_node = 32
    determined_outlet = get_watershed_outlet(grid, test_node)
    np.testing.assert_equal(determined_outlet, imposed_outlet)
    # Create a pit.
    pit_node = 38
    grid.at_node["topographic__elevation"][pit_node] -= 32
    fr.run_one_step()
    pit_outlet = get_watershed_outlet(grid, test_node)
    np.testing.assert_equal(pit_outlet, pit_node)