code: public void put(Interval1D<K> interval, V value) {
      Node<K, V> origNode = get(interval);
      if (origNode != null) {
        //System.err.println("Dupe is being put into the map. Interval: " + interval +
        //        "\n\tOld: " + origNode.getValue() + " New: " + value);
        origNode.setValue(value);
      } else {
        root = randomizedInsert(root, interval, value);
      }
    }
docs: Insert a new node in the tree. If the tree contained that interval already, the value is
  replaced.