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(define (make-eq-map)
(define alist '())
(define interned-alist '())
(define counter 0)
(lambda (msg obj)
(case msg
((contains?) (pair? (assq obj alist)))
((cycle-counter)
(set! interned-alist (cons obj interned-alist))
(let ((num (cdr (assq obj alist))))
(string->symbol (string-append
"#"
(number->string num)
"#"))))
((cycle-used?) (memq obj interned-alist))
((intern!)
(set! alist (cons (cons obj counter) alist))
(set! counter (+ counter 1)))
(else (error 'make-eq-map
"invalid message"
msg)))))
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