Tail Recursive Reverse Execution
>(trrev '(a b c d)) 1> (TRREVB (A B C D) NIL) 2> (TRREVB (B C D) (A)) 3> (TRREVB (C D) (B A)) 4> (TRREVB (D) (C B A)) 5> (TRREVB NIL (D C B A)) <5 (TRREVB (D C B A)) <4 (TRREVB (D C B A)) <3 (TRREVB (D C B A)) <2 (TRREVB (D C B A)) <1 (TRREVB (D C B A)) (D C B A)