; Lab 13: Final Review - Optional Questions

(define (has-cycle? s)
  (define (pair-tracker seen-so-far curr)
    (cond (_________________ ____________)
          (_________________ ____________)
          (else _________________________))
    )
  ______________________________
)

(define (contains? lst s)
  'YOUR-CODE-HERE
)

(define-macro (switch expr cases)
    'YOUR-CODE-HERE
)