code: function scheduleJob() {
    if (arguments.length < 2) {
      return null;
    }
  
    var name = (arguments.length >= 3 && typeof arguments[0] === 'string') ? arguments[0] : null;
    var spec = name ? arguments[1] : arguments[0];
    var method = name ? arguments[2] : arguments[1];
    var callback = name ? arguments[3] : arguments[2];
  
    var job = new Job(name, method, callback);
  
    if (job.schedule(spec)) {
      return job;
    }
  
    return null;
  }
docs: /* Convenience methods