code: function getPooledWarningPropertyDefinition(propName, getVal) {
    var isFunction = typeof getVal === 'function';
    return {
      configurable: true,
      set: set,
      get: get
    };
  
    function set(val) {
      var action = isFunction ? 'setting the method' : 'setting the property';
      warn(action, 'This is effectively a no-op');
      return val;
    }
  
    function get() {
      var action = isFunction ? 'accessing the method' : 'accessing the property';
      var result = isFunction ? 'This is a no-op function' : 'This is set to null';
      warn(action, result);
      return getVal;
    }
  
    function warn(action, result) {
      var warningCondition = false;
      warning(warningCondition, "This synthetic event is reused for performance reasons. If you're seeing this, " + "you're %s `%s` on a released/nullified synthetic event. %s. " + 'If you must keep the original synthetic event around, use event.persist(). ' + 'See https://fb.me/react-event-pooling for more information.', action, propName, result);
    }
  }
docs: Helper to nullify syntheticEvent instance properties when destructing
  
  @param {String} propName
  @param {?object} getVal
  @return {object} defineProperty object