docs: function (anchor) {
              var keys = anchor.split(" ");
              if (keys.length > 2) {
                  return false;
              }
  
              for (var i = 0, l = keys.length; i < l; i++) {
                  var key = keys[i];
                  if (!ariaUtilsArray.contains(this.ANCHOR_KEYS, key)) {
                      return false;
                  }
              }
  
              return true;
          }