External Authentication Script : What is the expected return value

Dear All ...

I'm learning on how to write external authentication script.

Learned from jcornez's filter at http://www.ejabberd.im/auth-script-filter-py ,
I knew (From "def from_ejabberd()) that , the final auth-script will need to handle an input format of :
auth:AAA:BBB:CCC ,
where :
AAA = username
BBB = Domain
CCC = password

My Question is for the last line --> to_ejabberd(result)

What values and in what kind of format that I have to store for "result" ?

Sincerely
-bino-