text: var Engine = require('./engine');
  var Wheel = require('./wheel');
  
  var Car = function() {
  	this.engine = new Engine();
  	this.wheel = new Wheel();
  }
  
  Car.prototype.run = function() {
  	this.engine.run();
  	var res = this.wheel.run();
  	console.log('run car...');
  	return 'car ' + res;
  }
  
  module.exports = Car;