> ./parent-child nok
datum is #t
80693: reading from 80694
80694: sleeping
80694: writing to parent
80694: bye
load: 0.30  cmd: parent-child 80693 [sbwait] 5.64r 0.00u 0.00s 0% 8132k
load: 0.30  cmd: parent-child 80693 [sbwait] 5.82r 0.00u 0.00s 0% 8132k
load: 0.30  cmd: parent-child 80693 [sbwait] 5.95r 0.00u 0.00s 0% 8132k
load: 0.30  cmd: parent-child 80693 [sbwait] 6.10r 0.00u 0.00s 0% 8132k
^C⏎