Please could anyone can help with this apparantly easy question on ADT's
The generic ADT named DIRECTORY(NI), where NI represents any ADT having a NAME operation returning a STRING. An example of NI is the ADT PERSON that has an operation called NAME which returns the name of a person as an instance of type STRING. The operations of the generic directory are as follows:-
CREATEDIR - creates an empty directory.
RETRIEVE - takes a directory and a name(i.e a string) as source and returns an item of NI as its result.
ADD - takes a directory and an item of NI and returns the directory with that item added.
ISINDIR - takes a directory and a name and returns TRUE if an item with that name is in the directory.
COUNT - takes a directory and return the number of items in that directory.
Using the constructive approach, write down the semantics of the RETRIEVE and COUNT operations. Use the ADT BSTree as an underlying model.