> (= 1 1)
#t
> (= #t 1)
=: contract violation
  expected: number?
  given: #t
> (eq? (cadr (list 1 2 2)) (caddr (list 1 2 2)))
#t
> (eq? (list 1 2 2) (list 1 2 2))
#f
> (eqv? "abc" "abc")
#t
> (eq? "abc" "abc")
#t
> (equal? (list 1 2 3) (list 1 2 3))
#t
> (equal? (list 1 + 3) (list 1 + 3))
#t
> (equal? (list 1 (lambda (x) x) 3) (list 1 (lambda (x) x) 3))
#f
> (eqv? "abc" "def")
#f
> (= "abc" "def")
=: contract violation
  expected: number?
  given: "abc"
> (define (id x) x)
> (equal? (list 1 id 3) (list 1 id 3))
#t
> (equal? (list 1 id 3) (list 1 (lambda (x) x) 3))
#f