public interface BST<T extends Comparable<T>> {
	/**
	* @return the root node of the tree ,
	* null if it is empty
	*/
	BinaryNode<T> getRoot ();

	/**
	* Update the root to n.
	* @param n the new root
	*/
	void setRoot ( BinaryNode<T> n);

	/** Traversal type 
	*/

	static enum Traversal {
	/** Visits current node first, sons after. 
	*/
	PREORDER,

	/** Visits left son first ,
	* current node after and right son last.
	* This visit is defined only for binary tree. 
	*/

	INORDER,

	/** Visits sons first, current node after 
	*/
	POSTORDER,
	
	/** 
	 * Visit the tree based on level 
	 */
	BREADTH,
	
	}

	/** Makes a visit operation on node n.
	* @param n node to visit 
	*/
	void visit (BinaryNode<T> n);

	/** Makes a type traversal of this tree.
	* For each node, calls #visit(Node).
	*
	* @param type a kind of traversal.
	*/
	void traversal (Traversal type);



	/** Puts item into the tree in a position that
	* preserves the natural order . . . . */
	void put( T item );

	/** Gets item.
	* @param item
	* @return the node that contains item if it is
	* present, null otherwise  */
	BinaryNode get(T item );

	/** Remove item */
	void remove (T item );




}