python implementation in code fragments through we define treemap class that implements the sorted map adt using binary search tree in factour implementation is more general we support all of the standard map operations (section )all additional sorted map operations (section )and positional operations including first)last)find position( )before( )after( )and delete(pour treemap class takes advantage of multiple inheritance for code reuseinheriting from the linkedbinarytree class of section for our representation as positional binary treeand from the mapbase class from code fragment of section to provide us with the key-value composite item and the concrete behaviors from the collections mutablemapping abstract base class we subclass the nested position class to support more specific keyand valueaccessors for our maprather than the elementsyntax inherited from the tree adt we define several nonpublic utilitiesmost notably subtree search(pkmethod that corresponds to the treesearch algorithm of code fragment that returns positionideally one that contains the key kor otherwise the last position that is visited on the search path we rely on the fact that the final position during an unsuccessful search is either the nearest key less than or the nearest key greater than this search utility becomes the basis for the public find position(kmethodand also for internal use when searchinginsertingor deleting items from mapas well as for the robust searches of the sorted map adt when making structural modifications to the treewe rely on nonpublic update methodssuch as add rightthat are inherited from the linkedbinarytree class (see section it is important that these inherited methods remain nonpublicas the search tree property could be violated through misuse of such operations finallywe note that our code is peppered with calls to presumed methods named rebalance insertrebalance deleteand rebalance access these methods serve as hooks for future use when balancing search treeswe discuss them in section we conclude with brief guide to the organization of our code code fragment beginning of treemap class including redefined position class and nonpublic search utilities code fragment positional methods first)last)before( )after( )and find position(paccessor code fragment selected methods of the sorted map adtfind min)find ge( )and find range(startstop)related methods are omitted for the sake of brevity code fragment getitem ( )setitem (kv)and iter code fragment deletion either by positionas delete( )or by keyas delitem (