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use clap::{arg, command};
fn main() {
let matches = command!() // requires `cargo` feature
.arg(
arg!(<MODE>)
.help("What mode to run the program in")
.value_parser(["fast", "slow"]),
)
.get_matches();
// Note, it's safe to call unwrap() because the arg is required
match matches
.get_one::<String>("MODE")
.expect("'MODE' is required and parsing will fail if its missing")
.as_str()
{
"fast" => {
println!("Hare");
}
"slow" => {
println!("Tortoise");
}
_ => unreachable!(),
}
}