错误消息错误#args：应该是“for start test next命令”来了

Question

尝试运行以下代码时收到错误消息wrong # args: should be "for start test next command：

proc finish {} {
        global ns nf
        $ns flush-trace
    #Close the trace file
        close $nf
    #Execute nam on the trace file
        exec nam out.nam &
        exit 0
}

#Create 50 nodes

for {set i 0} {$i<51} {incr i} {

set n($i) [$ns node]
}

#Create a duplex link between the nodes
$ns duplex-link $n0 $n1 1Mb 10ms DropTail