Consider the following description of an ADT that we will call a $$SmartDictionary$.$

Objects: A collection S of word objects, each object x in S has x$.$word being the word itself $($a string$)$ and x$.$meanings

being the list of meanings of the word $($a list of strings$).$

Operations:

$$ LookUp$($S$,$ w$)$: given a word string w$,$ return the list of meanings of the word; return NULL if the word does not

exist in the dictionary.

$$ AddMeaning$($S$,$ w$,$ m$)$: add the meaning string m for word w$.$ If word w does not exist in the dictionary, create a

new object for w in the dictionary and assign m as its first meaning.

$$ DeleteWord$($S$,$ w$)$: Remove word w from the dictionary, along with all its meanings. Do nothing if the word does

not exist in the dictionary