public void TreeNodeFollowsSawmillSpec()
{
var A = Tensor.ThreeD("A", (2, 2, 2), "a", out Index a, out Index b, out Index c)
.With(out Tensor B)
.With(out Tensor C);
ExpressionTree tree = (A[a, b] * B[b, a]).ToTree();
Children <ITreeNode> children = tree.Right.GetChildren();
Assert.Equal(tree.Right.Left, children.First);
Assert.Equal(tree.Right.Right, children.Second);
OperatorNode left = tree.CreateOperatorNode(tree.Right as OperatorNode, TensorOp.NoOp);
OperatorNode right = tree.CreateOperatorNode(tree.Right as OperatorNode, TensorOp.Sub);
tree.Right.SetChildren(Children.Two <ITreeNode>(left, right));
children = tree.Right.GetChildren();
Assert.Equal(left, children.First);
Assert.Equal(right, children.Second);
tree.Right.SetChildren(Children.Two <ITreeNode>(right, left)).SetChildren(Children.Two <ITreeNode>(right, left));
children = tree.Right.GetChildren();
Assert.Equal(right, children.First);
Assert.Equal(left, children.Second);
}