How to use the rc-menu.ItemGroup function in rc-menu

_react2["default"].Children.forEach(children, function (child) {
      if (!child) {
        return;
      }
      if (child.type.isSelectOptGroup) {
        var innerItems = _this2.renderFilterOptionsFromChildren(child.props.children, childrenKeys, menuItems);
        if (innerItems.length) {
          var label = child.props.label;
          var key = child.key;
          if (!key && typeof label === 'string') {
            key = label;
          } else if (!label && key) {
            label = key;
          }
          sel.push(_react2["default"].createElement(
            _rcMenu.ItemGroup,
            { key: key, title: label },
            innerItems
          ));
        }
        return;
      }

      (0, _warning2["default"])(child.type.isSelectOption, 'the children of `Select` should be `Select.Option` or `Select.OptGroup`, ' + ('instead of `' + (child.type.name || child.type.displayName || child.type) + '`.'));

      var childValue = (0, _util.getValuePropValue)(child);

      (0, _util.validateOptionValue)(childValue, _this2.props);

      if (_this2.filterOption(inputValue, child)) {
        var menuItem = _react2["default"].createElement(_MenuItem2["default"], _extends({
          style: _util.UNSELECTABLE_STYLE,

_react2['default'].Children.forEach(children, function (child) {
      if (!child) {
        return;
      }
      if (child.type.isSelectOptGroup) {
        var innerItems = _this2.renderFilterOptionsFromChildren(child.props.children, false);
        if (innerItems.length) {
          var label = child.props.label;
          var key = child.key;
          if (!key && typeof label === 'string') {
            key = label;
          } else if (!label && key) {
            label = key;
          }
          sel.push(_react2['default'].createElement(
            _rcMenu.ItemGroup,
            { key: key, title: label },
            innerItems
          ));
        }
        return;
      }

      (0, _warning2['default'])(child.type.isSelectOption, 'the children of `Select` should be `Select.Option` or `Select.OptGroup`, ' + ('instead of `' + (child.type.name || child.type.displayName || child.type) + '`.'));

      var childValue = (0, _util.getValuePropValue)(child);
      if (_this2.filterOption(inputValue, child)) {
        sel.push(_react2['default'].createElement(_rcMenu.Item, (0, _extends3['default'])({
          style: _util.UNSELECTABLE_STYLE,
          attribute: _util.UNSELECTABLE_ATTRIBUTE,
          value: childValue,
          key: childValue

_react2['default'].Children.forEach(menuItems, function (item) {
    if (item.type === _rcMenu.ItemGroup) {
      selectedKeys = selectedKeys.concat(getSelectKeys(item.props.children, value));
    } else {
      var itemValue = getValuePropValue(item);
      var itemKey = item.key;
      if (value.indexOf(itemValue) !== -1 && itemKey) {
        selectedKeys.push(itemKey);
      }
    }
  });
  return selectedKeys;

clonedMenuItems = menuItems.map(function (item) {
              if (item.type === _rcMenu.ItemGroup) {
                var children = item.props.children.map(clone);
                return (0, _react.cloneElement)(item, {}, children);
              }
              return clone(item);
            });
          })();

_react2['default'].Children.forEach(children, function (child) {
      if (child.type === _OptGroup2['default']) {
        var innerItems = _this.renderFilterOptionsFromChildren(child.props.children, false);
        if (innerItems.length) {
          var label = child.props.label;
          var key = child.key;
          if (!key && typeof label === 'string') {
            key = label;
          } else if (!label && key) {
            label = key;
          }
          sel.push(_react2['default'].createElement(
            _rcMenu.ItemGroup,
            { key: key, title: label },
            innerItems
          ));
        }
        return;
      }
      var childValue = (0, _util.getValuePropValue)(child);
      if (_this.filterOption(inputValue, child)) {
        sel.push(_react2['default'].createElement(_rcMenu.Item, _extends({
          style: _util.UNSELECTABLE_STYLE,
          attribute: _util.UNSELECTABLE_ATTRIBUTE,
          value: childValue,
          key: childValue
        }, child.props)));
      }
      if (tags && !child.props.disabled) {

menuProps.openTransitionName = menuOpenAnimation;
            } else {
                menuProps.openAnimation = menuOpenAnimation;
            }
            return _react2['default'].createElement(_rcMenu2['default'], (0, _extends3['default'])({}, this.props, menuProps));
        }
    }]);
    return Menu;
}(_react2['default'].Component);

exports['default'] = Menu;

Menu.Divider = _rcMenu.Divider;
Menu.Item = _MenuItem2['default'];
Menu.SubMenu = _rcMenu.SubMenu;
Menu.ItemGroup = _rcMenu.ItemGroup;
Menu.defaultProps = {
    prefixCls: 'ant-menu',
    className: '',
    theme: 'light'
};
Menu.childContextTypes = {
    inlineCollapsed: _propTypes2['default'].bool
};
Menu.contextTypes = {
    siderCollapsed: _propTypes2['default'].bool
};
module.exports = exports['default'];

menuProps.openTransitionName = menuOpenAnimation;
            } else {
                menuProps.openAnimation = menuOpenAnimation;
            }
            return _react2['default'].createElement(_rcMenu2['default'], (0, _extends3['default'])({}, this.props, menuProps));
        }
    }]);
    return Menu;
}(_react2['default'].Component);

exports['default'] = Menu;

Menu.Divider = _rcMenu.Divider;
Menu.Item = _MenuItem2['default'];
Menu.SubMenu = _rcMenu.SubMenu;
Menu.ItemGroup = _rcMenu.ItemGroup;
Menu.defaultProps = {
    prefixCls: 'ant-menu',
    className: '',
    theme: 'light'
};
Menu.childContextTypes = {
    inlineCollapsed: _propTypes2['default'].bool
};
Menu.contextTypes = {
    siderCollapsed: _propTypes2['default'].bool
};
module.exports = exports['default'];