code: def get_object_header(self, ref):
          
          cmd = self._get_persistent_cmd("cat_file_header", "cat_file", batch_check=True)
          return self.__get_object_header(cmd, ref)
docs: Use this method to quickly examine the type and size of the object behind
          the given ref.
  
          :note: The method will only suffer from the costs of command invocation
              once and reuses the command in subsequent calls.
  
          :return: (hexsha, type_string, size_as_int)