How to use the elfi.old.graph.Node function in elfi

def test_remove(self):
        a = Node('a')
        b = Node('b')
        c = Node('c', a, b)
        d = Node('d', c)
        e = Node('e', c)
        c.remove(keep_parents=False, keep_children=False)
        assert c.children == []
        assert c.parents == []
        assert b.children == []
        assert e.parents == []

def test_remove(self):
        a = Node('a')
        b = Node('b')
        c = Node('c', a, b)
        d = Node('d', c)
        e = Node('e', c)
        c.remove(keep_parents=False, keep_children=False)
        assert c.children == []
        assert c.parents == []
        assert b.children == []
        assert e.parents == []

def test_construction_add_index(self):
        b = Node('b')
        c = Node('c', b)
        d = Node('d')
        e = Node('e')
        c.add_parent(d, index=0, index_child=0)
        assert c.parents == [d, b]
        assert b.children == [c]
        assert d.children == [c]
        b._add_child(e, index=0)
        assert b.children == [e, c]
        assert e.parents == []  # _add_child doesn't call add_parent

def test_component(self):
        a = Node('a')
        b = Node('b')
        c = Node('c', b)
        d = Node('d', a, c)
        e = Node('e', d)
        f = Node('f', d, c)
        g = Node('g', e, f)
        ext = Node('ext')
        assert set(c.component) == {a, b, c, d, e, f, g}
        assert set(g.component) == {a, b, c, d, e, f, g}
        assert ext.component == [ext]

def test_component(self):
        a = Node('a')
        b = Node('b')
        c = Node('c', b)
        d = Node('d', a, c)
        e = Node('e', d)
        f = Node('f', d, c)
        g = Node('g', e, f)
        ext = Node('ext')
        assert set(c.component) == {a, b, c, d, e, f, g}
        assert set(g.component) == {a, b, c, d, e, f, g}
        assert ext.component == [ext]

def test_remove_parent(self):
        a = Node('a')
        b = Node('b', a)
        c = Node('c', b)
        c.remove_parent(0)
        assert c.parents == []
        assert b.children == []
        b.remove_parent(a)
        assert b.parents == []
        assert a.children == []

def test_construction_add_index(self):
        b = Node('b')
        c = Node('c', b)
        d = Node('d')
        e = Node('e')
        c.add_parent(d, index=0, index_child=0)
        assert c.parents == [d, b]
        assert b.children == [c]
        assert d.children == [c]
        b._add_child(e, index=0)
        assert b.children == [e, c]
        assert e.parents == []  # _add_child doesn't call add_parent

def test_consistent_order(self):
        def assert_order(node, attr):
            prev = getattr(node, attr)
            assert isinstance(prev, list)
            for i in range(10):
                cur = getattr(node, attr)
                assert prev == cur
                prev = cur
        a = Node('a')
        b = Node('b')
        c = Node('c', b)
        d = Node('d', a, c)
        e = Node('e', d)
        f = Node('f', d, c)
        g = Node('g', e, f)
        assert_order(g, "component")
        assert_order(g, "ancestors")
        assert_order(g, "parents")
        assert_order(a, "children")
        assert_order(a, "descendants")

def test_none_parent(self):
        a = Node('a', None)
        assert a.parents == []

def test_change_to(self):
        a = Node('a')
        b = Node('b')
        c = Node('c', a, b)
        d = Node('d', c)
        e = Node('e', c)
        f = Node('f')
        c_new = Node('c_new', a, f)
        c = c.change_to(c_new, transfer_parents=False, transfer_children=True)
        assert c.parents == [a, f]
        assert c.children == [d, e]
        c_new2 = Node('c_new2', a)
        c = c.change_to(c_new2, transfer_parents=True, transfer_children=False)
        assert c.parents == [a, f]
        assert c.children == []