code: function Worker(baseUrl, opts = {}) {
  
    if (!(this instanceof Worker)) {
      return new Worker(baseUrl, opts);
    }
  
    // inheritance
    Emitter.call(this);
  
    this.options = extend({
      workerId: uuid.v4()
    }, defaultOptions, opts);
  
    this.subscriptions = {};
  
    this.state = STATE_NEW;
  
    // apply extensions
    if (this.options.use) {
      this.extend(this.options.use);
    }
  
    // local variables
    this.engineApi = new EngineApi(
      baseUrl,
      this.options.requestOptions,
      this.options.apiVersion
    );
  
    if (this.options.pollingDelay) {
      throw new Error('options.pollingDelay got replaced with options.autoPoll');
    }
  
    // start
    if (this.options.autoPoll) {
      this.start();
    }
  }
docs: Instantiate a worker.
  
  @param {String} baseUrl
  @param {Object} [opts={}]