vendor/structopt-0.2.18/examples/at_least_two.rs

#[macro_use]
extern crate structopt;

use structopt::StructOpt;

#[derive(StructOpt, Debug)]
struct Opt {
    #[structopt(raw(required = "true", min_values = "2"))]
    foos: Vec<String>,
}

fn main() {
    let opt = Opt::from_args();
    println!("{:?}", opt);
}