src/main/java/com/workplacesystems/utilsj/collections/TransactionalBidiTreeMap.java
private static <K,V> Node<K,V> getLeftChild(final Node<K,V> node, final int index) {

        return (node == null)
               ? null
               : node.getLeft(index);
    }
private static <K,V> Node<K,V> getLeftChild(final Node<K,V> node, final int index) {

        return (node == null)
               ? null
               : node.getLeft(index);
    }
get a node's left child. mind you, the node may not exist. no
problem

@param node the node (may be null) in question
@param index KEY or VALUE