Customary way to display arg examples / samples / hints in command usage?

[alcroito]

Is there a customary way to display a sample value for an Arg? Is it up to the developer to specify it manually in Arg::help? Or is there a better way?

E.g.

-d, --domain <DOMAIN>               The domain to use. Example: 'foo.net'

Is

        Arg::with_name("domain")
                .short("d")
                .long("domain")
                .value_name("DOMAIN")
                .help("The domain to use. Example: 'foo.net'")
                .takes_value(true),

as good as it gets?

[ldm0]

Currently no I guess. What does the "better way" looks like?

[alcroito]

I was thinking maybe there might be a .sample() or .example() or .usage_hint() method that would print the example in some standard way.

[ldm0]

I mean what the output looks like. Some example would be great.

[alcroito]

I'm not sure what the output should look like. That's the reason for my question, in case something nice and standardized that appeals to the community already exists. :)