The number of nodes in this tree or subtree.
The index of this node.
Returns whether the tree or subtree is empty.
The "left" subtree.
The value of the node containing the maximum value
The index of the node containing the maximum value within the subtree.
The value of the node containing the minimum value
The "right" subtree.
Converts the tree to a list.
The value associated with this node.
Singleton object representing a nonexistent child of a terminal node.