lib/plugin-templates.js
function engine(path, options, fn) {
  options.filename = path;

  fs.readFile(path, 'utf8', function (err, str) {
    if (err) return fn(err);
    engine.render(str, options, fn);
  });
}
function engine(path, options, fn) {
  options.filename = path;

  fs.readFile(path, 'utf8', function (err, str) {
    if (err) return fn(err);
    engine.render(str, options, fn);
  });
}
function engine ( path , options , fn ) { options . filename = path ; fs . readFile ( path , 'utf8' , function ( err , str ) { if ( err ) return fn ( err ) ; engine . render ( str , options , fn ) ; } ) ; }
Express 3 Template Engine
Express 3 Template Engine