private void KDistanceFromRootRec(BTPosition<T> current, int k) {

		if (current == null)
			return;
		if (k == 0) {
			System.out.println("find one at " + current.element());
		} else {
			KDistanceFromRootRec(current.getLeft(), k - 1);// note: can't use
															// --k here, it will
															// affect the blow
															// line's k
			KDistanceFromRootRec(current.getRight(), k - 1);
		}

		/**
		 * second thought: use BFS to get them
		 */

		/**
		 * follow up start from any node, get k distance?
		 */
	}