Rules for last-pair

Define rules to implement the last-pair operation of exercise 2.17 , which returns a list containing the last element of a nonempty list. Check your rules on queries such as (last-pair (3) ?x) , (last-pair (1 2 3) ?x) , and (last-pair (2 ?x) (3)) . Do your rules work correctly on queries such as (last-pair ?x (3)) ?

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