We want to create a structure that will represent a deck of cards  (not necessarily full). Each card has a character (between  '2'  to  '9' and  'T',  'J',  'Q',  'K',  'A') and a suit (diamonds, hearts, clubs, spades):

a)  Choose a representation for each card and also for the deck of cards (it can be empty or non-empty)

b)  Define an add_card predicate that takes a card and a deck and adds the card if it is not already there (i.e. no duplicates) creating a new deck of cards. If the card is not of a valid suit or number this predicate will simply do nothing.