engines/jade.js
function Jade() {
  
  var opts = (app.config.engines && app.config.engines.jade) || {};
  
  this.options = protos.extend({
    pretty: true
  }, opts);
  
  this.module = jade;
  this.multiPart = false;
  this.extensions = ['jade', 'jade.html'];

}
function Jade() {
  
  var opts = (app.config.engines && app.config.engines.jade) || {};
  
  this.options = protos.extend({
    pretty: true
  }, opts);
  
  this.module = jade;
  this.multiPart = false;
  this.extensions = ['jade', 'jade.html'];

}
function Jade ( ) { var opts = ( app . config . engines && app . config . engines . jade ) || { } ; this . options = protos . extend ( { pretty : true } , opts ) ; this . module = jade ; this . multiPart = false ; this . extensions = [ 'jade' , 'jade.html' ] ; }
Jade engine class

https://github.com/visionmedia/jade
Jade engine class