Function getopts::optoptUnstable

pub fn optopt(short_name: &str, long_name: &str, desc: &str, hint: &str) -> OptGroup

Create a long option that is optional and takes an argument.

• short_name - e.g. "h" for a -h option, or "" for none
• long_name - e.g. "help" for a --help option, or "" for none
• desc - Description for usage help
• hint - Hint that is used in place of the argument in the usage help, e.g. "FILE" for a -o FILE option