private Tree234Node goNext(Tree234Node currentNode, int key) {
	  if (key < currentNode.key1) {
		  return currentNode.child1;
	  } else if (key == currentNode.key1) {
		  return null;
	  } else if ((currentNode.keys == 1) || (key < currentNode.key2)) {
		  return currentNode.child2;
	  } else if (key == currentNode.key2) {
		  return null;
	  } else if ((currentNode.keys == 2) || (key < currentNode.key3)) {
		  return currentNode.child3;
	  } else if (key == currentNode.key3) {
		  return null;
	  } else {
		  return currentNode.child4;
	  }
  }