1use clap::{arg, command};
2
3fn main() {
4 let matches = command!() // requires `cargo` feature
5 .arg(
6 arg!(<MODE>)
7 .help("What mode to run the program in")
8 .value_parser(["fast", "slow"]),
9 )
10 .get_matches();
11
12 // Note, it's safe to call unwrap() because the arg is required
13 match matches
14 .get_one::<String>("MODE")
15 .expect("'MODE' is required and parsing will fail if its missing")
16 .as_str()
17 {
18 "fast" => {
19 println!("Hare");
20 }
21 "slow" => {
22 println!("Tortoise");
23 }
24 _ => unreachable!(),
25 }
26}
27