Constructing the following tree:

          null
         /    \
        1      2
      / | \    |
     3  4  5   6

preorder:	null 1 3 4 5 2 6 

pre/steps:	1 3 4 5 2 6 null 

inorder:	1 1 null 

postorder:	3 4 5 1 6 2 null 

post/steps:	3 4 5 1 6 2 null 

(pre+in):	null 1 3 1 4 1 5 null 2 6 

(in+post):	3 1 4 1 5 1 null 6 2 null 

(pre+post):	null 1 3 3 4 4 5 5 1 2 6 6 2 null 

(pre+in+post):	null 1 3 3 1 4 4 1 5 5 1 null 2 6 6 2 null 

eulertour:	null 1 3 1 4 1 5 1 null 2 6 2 null 

And now for a binary tree:

          null
         /    \
        1      2
      /  \    / \
     3    4  5   6

preorder:	null 1 3 4 2 5 6 

inorder:	3 1 4 null 5 2 6 

in/steps:	5 2 6 3 1 4 null 

postorder:	3 4 1 5 6 2 null 

(pre+in):	null 1 3 3 1 4 4 null 2 5 5 2 6 6 

(in+post):	3 3 1 4 4 1 null 5 5 2 6 6 2 null 

(pre+post):	null 1 3 3 4 4 1 2 5 5 6 6 2 null 

(pre+in+post):	null 1 3 3 3 1 4 4 4 1 null 2 5 5 5 2 6 6 6 2 null 

eulertour:	null 1 3 1 4 1 null 2 5 2 6 2 null