ob key getNode node-value ob is a class object or an array. The operator getNode returns the node with the key in ob. When ob is a class, the node is an array of the format [key attr-list node-list] When ob is an array, the node is a value of key-value pairs. Example: /dog [(dog) [[(legs) 4] ] [ ]] [(class) (tree)] dc def /man [(man) [[(legs) 2] ] [ ]] [(class) (tree)] dc def /ma [(mammal) [ ] [man dog]] [(class) (tree)] dc def ma (dog) getNode Example 2: [ [1 ] [2 3] [[(dog) 2]]] (dog) getNode ::