docs: function(config) {
    config = config || {};
  
    config.headers = config.headers || {};
    if (!config.headers.Accept) {
      config.headers.Accept = 'application/hal+json, application/json; q=0.5';
    }
  
    if (!config.baseUrl) {
      throw new Error('HttpClient needs a `baseUrl` configuration property.');
    }
  
    Events.attach(this);
  
    this.config = config;
  }