def METHOD_NAME(Grid):
    grid = Grid((4, 5))
    grid.status_at_node[13] = grid.BC_NODE_IS_FIXED_VALUE
    grid.status_at_node[2] = grid.BC_NODE_IS_CLOSED
    value_at_node = np.arange(grid.number_of_nodes, dtype=float)
    coef_at_link = np.full(grid.number_of_links, 1.0, dtype=float)
    expected, _ = get_core_node_matrix(grid, value_at_node, coef_at_link=coef_at_link)
    actual, _ = get_core_node_matrix(grid, value_at_node)
    assert_array_equal(expected.toarray(), actual.toarray())