update

Task/Queue-Usage/Racket/queue-usage.rkt

@@ -0,0 +1,17 @@
+#lang racket
+
+(require data/queue)
+
+(define queue (make-queue))
+
+(enqueue! queue 'black)
+(queue-empty? queue) ; #f
+
+(enqueue! queue 'red)
+(enqueue! queue 'green)
+
+(dequeue! queue) ; 'black
+(dequeue! queue) ; 'red
+(dequeue! queue) ; 'green
+
+(queue-empty? queue) ; #t