parsing tree from excel sheet

[Peter Otten]

Peter Otten wrote:

> [A, A1, A21, A22]
> 
> Finally the append_nodes(A3, nodes) will append A3 and then return because
> it has no children, and we end up with
> 
> nodes = [A, A1, A21, A22, A3]
 
Yay, proofreading! Both lists should contain A2:

[A, A1, A2, A21, A22]

nodes = [A, A1, A2, A21, A22, A3]