File: SASS_REFERENCE

I've became a SASS @extend addicted. So far the HTML looks a lot more semantic with fewer styling related classes.

Whether an error in the Sass code should cause Sass to provide a detailed description within the generated CSS file. If set to true, the error will be displayed along with a line number and source snippet both as a comment in the CSS file and at the top of the page (in supported browsers). Otherwise, an exception will be raised in the Ruby code. Defaults to false in production mode, true otherwise. Only has meaning within Rack, Ruby on Rails, or Merb.

Full article: http://sass-lang.com/docs/yardoc/file.SASS_REFERENCE.html