code: def show_tree(self, has_tree=False, force_update=False):
          
          if has_tree:
              self.has_tree = self.clear_tree()
  
          if force_update:
              self.data_refresh_flag = True
  
          try:
              if self.data_refresh_flag:
                  fn = self.open_filename
                  if self.get_filetype(fn).lower() == 'json':
                      data_dict = self.read_json(fn)
                  elif self.get_filetype(fn).lower() == 'lte':
                      data_dict = self.read_lte(fn)
              else:
                  data_dict = self.data['dict']
  
              tree_name = self.treename_tc.GetValue()
              tree_root = self.mainview_tree.AddRoot(tree_name)
              self.add_items(data_dict,
                             root=tree_root,
                             target=self.mainview_tree)
              self.expand_tree(self.expand_all_flag)
              self.update_stat('list tree', 'Listing tree succeed', 'OK')
              self.tree_refresh_flag = False
              self.set_title()
              self.all_children = self.get_children(tree_root,
                                                    self.mainview_tree)
              self.found_items_clear = True  # set clear flag of found items
              self.lattice_model = None  # reset model when open new file
              return True
          except:
              self.update_stat('list tree', 'Listing tree failed', 'ERR')
              return self.has_tree
docs: show tree list
  
          :param has_tree: tree exist or not, False by default, if True, tree should be cleared first
          :param force_update: force update flag, if True, update neglect other flags.
          :return: has_tree, True successful, not change when exception