testing for example nodes
public static void main ( String args [ ] ) { BinaryTree tree = new BinaryTree ( ) ; tree . root = new Node ( 12 ) ; tree . root . left = new Node ( 10 ) ; tree . root . right = new Node ( 30 ) ; tree . root . right . left = new Node ( 25 ) ; tree . root . right . right = new Node ( 40 ) ; tree . leftView ( ) ; } }