Is Leap year #scheme

leap.scm

(import (rnrs (6)))
(use-modules ((rnrs) :version (6)))

(define (leap-year? year)
  (if (and (divisible? year 4) (not (divisible? year 100)))
      #t
      (if (divisible? year 400)
          #t
          #f)))

I think you only need to provide the divisible? function

(define (divisible? n x)
  (zero? (remainder n x)))

and skip the imports in the beginning. I think they only work for guile scheme