docs: def get_callable(subcommand):
      # type: (config.RcliEntryPoint) -> Union[FunctionType, MethodType]
      """Return a callable object from the subcommand.
  
      Args:
          subcommand: A object loaded from an entry point. May be a module,
              class, or function.
  
      Returns:
          The callable entry point for the subcommand. If the subcommand is a
          function, it will be returned unchanged. If the subcommand is a module
          or a class, an instance of the command class will be returned.
  
      Raises:
          AssertionError: Raised when a module entry point does not have a
              callable class named Command.
      """
      _LOGGER.debug(
          'Creating callable from subcommand "%s".', subcommand.__name__)
      if isinstance(subcommand, ModuleType):
          _LOGGER.debug('Subcommand is a module.')
          assert hasattr(subcommand, 'Command'), (
              'Module subcommand must have callable "Command" class definition.')
          callable_ = subcommand.Command  # type: ignore
      else:
          callable_ = subcommand
      if any(isinstance(callable_, t) for t in six.class_types):
          return callable_()
      return callable_