examples/ex-36.rkt
#lang racket
(require (planet wcy/mpost-wrapper))
(provide main)
(define (A-B-C)
  (values (point 0 0)
          (point '1cm 0)
          (point 0 '1cm)))
(define (main)
  (call-with-values A-B-C
    (lambda (A B C)
      (draw (op-- A B C 'cycle))
      (for ((a-point (in-list (list A B C))))
           (fill (fullcircle  '4bp a-point) #:withcolor 'white))
      (for ((a-point (in-list (list A B C))))
           (draw  (fullcircle  '4bp a-point))))))