How to config cookie-only sessions in pylons?

I want to use cookie-only sessions in pylons. I have found some documents for this problem, but unfortunately, they said a lot, but where and how to config it.

http://pylonshq.com/docs/en/0.9.7/sessions/

http://wiki.pylonshq.com/display/be开发者_开发技巧aker/Cookie-Only+Sessions

I'm new to pylons, and I don't know how to config. Somebody can help me? Thanks!

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OK, I found it in development.ini