after 500
    fconfigure $sock -blocking 0
    set result a:[gets $sock]
    lappend result b:[gets $sock]
    fconfigure $sock -blocking 1
    puts $s2 two
    flush $s2
    fconfigure $sock -blocking 0
    lappend result c:[gets $sock]
    fconfigure $sock -blocking 1
    close $s2
    close $s
    close $sock
    set result
} {a:one b: c:two}