code: function(config) {
    this.events = new EventEmitter();
    this.config = config || {};
  
    // Allow someone to change the complete event label.
    if (!this.config.complete) {
      this.config.complete = '__complete';
    }
  
    debug('Chain created with the following configuration: ' + JSON.stringify(this.config));
  }
docs: The primary container for chained events.
  
  @param config
  An optional configuration object.
  
  @constructor