public static boolean compare(Node lhs, Node rhs) {
			// search each node in trees Depth first.
			if (lhs == null) {
				return (rhs == null) ? true : false;
			} else {
				if (rhs == null) {
					return false;
				}
			}
			if (lhs.data == rhs.data) {
				if (compare(lhs.left, rhs.left)) {
					return compare(lhs.right, rhs.right);
		        } else {
		        	return false;
		        }
			} else {
				return false;
			}
		}