* A node that can be stored in a {@link Tree}. A node has exactly one parent
* (which is <code>null</code> if the node is the {@link Tree#getRootNode()}
* of the tree) and an arbitrary amount of child nodes.
* A node that can be stored in a {@link Tree}. A node has exactly one parent
* (which is <code>null</code> if the node is the {@link Tree#getRootNode()}
* of the tree) and an arbitrary amount of child nodes.