text: function Observer(callback) {
      return function (target, propertyKey) {
          const defaultUpdatedCallback = target.updated;
          target.updated = function (changedProperties) {
              if (defaultUpdatedCallback)
                  defaultUpdatedCallback.call(this, changedProperties);
              if (changedProperties.has(propertyKey)) {
                  if (callback) {
                      callback && typeof callback === "string" ?
                          this[callback].bind(this)(this[propertyKey], changedProperties.get(propertyKey)) :
                          callback.bind(this)(this[propertyKey], changedProperties.get(propertyKey));
                  }
              }
          };
      };
  }
  export { Observer };
  //# sourceMappingURL=PropertyObserver.js.map