This is particularly handy when combined with `clap::value_t`.

Here's demo of it working with Clap:

```bash
cargo +stable init --bin tonic-demo
cd tonic-demo
cat <<-EOF >> Cargo.toml
  clap = "*"
  tonic = { path = "../hyperium/tonic/tonic" }
EOF
cat <<-EOF > src/main.rs
    use clap::{value_t, App, Arg};
    use tonic::transport::Endpoint;
    fn main() {
        let matches = App::new("tonic-demo")
            .arg(Arg::with_name("host"))
            .get_matches();
        let x = value_t!(matches.value_of("host"), Endpoint);
        println!("{:?}", x);
    }
EOF
cargo +stable run -- https://127.0.0.1:443
```

Signed-off-by: Ana Hobden <[email protected]>