code: function _createXhr(method, url, options) {
      var xhr = new XMLHttpRequest();
  
      xhr.open(method, url);
  
      // Setup headers, including the *Authorization* that holds the Api Key.
      for (var header in options.headers) {
        if (options.headers.hasOwnProperty(header)) {
          xhr.setRequestHeader(header, options.headers[header]);
        }
      }
  
      // Set timeout.
      if (options.timeout > 0) {
        xhr.timeout = options.timeout;
      }
  
      return xhr;
    }
docs: Create an asynchronous XHR2 object.