In node js how to write map/reduce views in couchdb using sag javascript library

In my node application i need to write map/reduce views in couchdb using sag javascript library(https://github.com/sbisbee/sag-js/blob/master/tests/sag-tests.js). How can i do this.I have gone through the document(http://www.saggingcouch.com/jsdocs.php) in that they haven't mentioned clearly about this.