docs: def _add_arguments(self, args):
          """
          Add command line arguments to each section in config.
          e.x:
          before:
              [global]
              hoge = hoge
  
          after:
              {
                  'global': {
                      'hoge': 'hoge',
                      'arguments': {
                          'debug_mode': True,
                          'and_more': AND_MORE
                      }
                  }
              }
          """
          update_dict = {
              'arguments': vars(args)
          }
          for section in self.config.keys():
              self.config[section].update(update_dict)