use std::collections::HashMap;
type CreateBox = fn() -> i32;
fn frontier_fn() -> i32 {
    1
}
fn homestead_fn() -> i32 {
    2
}

fn main() {
    let patch_opts: HashMap<&str, CreateBox> =
        [("frontier", frontier_fn as CreateBox), ("homestead", homestead_fn)]
            .iter()
            .cloned()
            .collect();
    let opt = "frontier";
    match patch_opts.get(&opt) {
        Some(patch_fn) => println!("Result: {}", patch_fn()),
        None => println!("Option {} not found", opt),
    }
}