Web爬蟲問題

大家好 我是剛開始學習Golang的新手

請問我該如何按照題目描述去這個網站進行爬蟲，謝謝大家
Your job is to design and create a CLI application that will parser www.alexa.com data. The application signature should look like the following:
$ ./clawer […]
The application must be able to accept these actions as param and perform the corresponding tasks:  top : show top sites URL on www.alexa.com
 country : show top 20 sites URL on www.alexa.com by country
e.g.
$ ./clawer top
$ ./clawer country
The application needs to have an extensible interface where adding a new action is just a matter of adding more files and should not require any modifications to the existing code base.
ps. If anything is unclear, you may set a reasonable assumption and state it at the beginning of the situation.