How to achieve auto completion after user input a not fix parameter?

[li9270]

For example, the command may be:
get 0 status
get 0 config
get 1 status
get 1 config
The first cmd get is fix, the second cmd is not fix, may 0, or 1, 2, 3 ......, the third cmd is fix, may status or config.
The wanted result: I input the cmd "get 0", the press the tab, I want to get prompt: status config.
But I have not find out the modify methord.
Did anyone has any suggestion? Thanks a lot !