// there are 2 cases, as node could be at the end, or the one before the end
      else if (traverseInOrder.successor == null) {
          // this condition is here because if traverse.successor is null, traversal is not incremented
          if (iterator.key.compareTo(traverseInOrder.key) < 0) {
              traverseInOrder.predecessor.successor = iterator;
              iterator.predecessor = traverseInOrder.predecessor;
              iterator.successor = traverseInOrder;
              traverseInOrder.predecessor = iterator;
          } 
          // this covers the case when successor is null, but the key to insert is greater
          else { 
              iterator.predecessor = traverseInOrder;
              traverseInOrder.successor = iterator; 
              //iterator.successor = null // **even if I put this here, nothing happens**
          }
      }