Adds items in data as a submenu to parent

def _add_submenu(self, parent, data):
        """Adds items in data as a submenu to parent"""

        for item in data:
            obj = item[0]
            if obj == wx.Menu:
                try:
                    __, menuname, submenu, menu_id = item
                except ValueError:
                    __, menuname, submenu = item
                    menu_id = -1

                menu = obj()
                self._add_submenu(menu, submenu)

                if parent == self:
                    self.menubar.Append(menu, menuname)
                else:
                    parent.AppendMenu(menu_id, menuname, menu)

            elif obj == wx.MenuItem:
                try:
                    msgtype, shortcut, helptext, item_id = item[1]
                except ValueError:
                    msgtype, shortcut, helptext = item[1]
                    item_id = wx.NewId()

                try:
                    style = item[2]
                except IndexError:
                    style = wx.ITEM_NORMAL

                menuitem = obj(parent, item_id, shortcut, helptext, style)
                self.shortcut2menuitem[shortcut] = menuitem
                self.id2menuitem[item_id] = menuitem

                parent.AppendItem(menuitem)

                self.ids_msgs[item_id] = msgtype

                self.parent.Bind(wx.EVT_MENU, self.OnMenu, id=item_id)

            elif obj == "Separator":
                parent.AppendSeparator()

            else:
                raise TypeError(_("Menu item unknown"))