def option(self, *args, **kwargs):
        """
        Registers a click.option which falls back to a configmanager Item
        if user hasn't provided a value in the command line.

        Item must be the last of ``args``.

        Examples::

            config = Config({'greeting': 'Hello'})

            @click.command()
            @config.click.option('--greeting', config.greeting)
            def say_hello(greeting):
                click.echo(greeting)

        """
        args, kwargs = _config_parameter(args, kwargs)
        return self._click.option(*args, **kwargs)