func handleConn(c net.Conn) {
var wg sync.WaitGroup
input := bufio.NewScanner(c)
for input.Scan() {
wg.Add(1)
go func() {
defer wg.Done()
echo(c, input.Text(), 1*time.Second)
}()
go func() {
wg.Wait()
if c, ok := c.(*net.TCPConn); ok {
c.CloseWrite()
}
}()
}
}