We've already seen how to use an anonymous subroutine or a reference to a named subroutine. 我们已经看到如何使用匿名的子例程或者对指定子例程的引用。
This is useful for building subroutine structures while you bring your documentational reference to the foreground for API information. 这对构建子例程架构的同时还要在显著位置打开文档参考以获得API信息来说很有用。