Tree question

Anybody knows how to realize a tree node? For example,there are two node in a tree,like follows:

+Parent Node1
+Parent Node2

When click Parent Node1,the tree changed to follows:
-Parent Node1
　+Child Node1
　+Child Node2
　-Leave Node
+Parent Node2

In above tree,it can add new Parent Node or Child Node and can modify and delete it.I am puzzled with this question for a long time.How to realize it? Are there some open source code for this question?

Thanks in advance.

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