(require-extension coops)
(require-extension coops-introspection)

(define-class <a> ())

(define a (make <a>))

(print a (instance-of? a <a>))

(define-class <a> ())

(print a (instance-of? a <a>))

;; Output
;; #<coops instance of `<a>'>#t
;; #<coops instance of `<a>'>#f