ExpressJS 4.0 has been released(expressjs.com)

    #!/usr/bin/env node --harmony
    var fs = require('fs'),
      co = require('co'),
      thunkify = require('thunkify'),
      request = require('request'),
      readFile = thunkify(fs.readFile);
      get = thunkify(request.get);

    var log = console.log.bind(console);

    // Create a thunk, and run it immediately.
    co(function *(){
      try {
        var fileContents = yield readFile('myfile', 'utf8');
        log(fileContents);
        var yahoo = (yield get('http://yahoo.com'))[0];
        log(yahoo.statusCode)
      } catch(error) {
        log('Oh no, an error!')
        log(error.code)
      }
    })()