#;1> (use channel)
#;2> (define c (make-channel)) (thread-start! (lambda () (thread-sleep! 5) (channel-enqueue c 1)))
#<thread: thread46>
#;4> (channel-receive c 2)
#f
#;5> (channel-receive c 2)
#f
#;6> (channel-receive c 2)
1
#;7>