Next, notice the namedargument constructor for frame.
接下来,注意frame的命名参数构造器。
2
The request URI can be retrieved as well as the argument values of named parameters.
我们可以获得请求的URI以及参数的名值对。
3
This does the same as example 1, but in this case, selpg is reading its stdin, which has been redirected by the shell/kernel to come from "input_file" instead of an explicitly named filename argument.