const GROUND: i64 = 0;
const SHALLOW: i64 = 1;
const DEEP: i64 = 4;
const LAVA: i64 = 7;
fn terrain(t: i64) -> &'static str {
    match t {
        GROUND => "ground",
        x if (SHALLOW..DEEP).contains(&x) => "water", // 1, 2, 3
        LAVA | 10..=11 => "hot",                    // 7, 10, 11
        _ => "rock",
    }
}

fn main() { for (n,want) in [(0,"ground"),(1,"water"),(3,"water"),(4,"rock"),(7,"hot"),(9,"rock"),(10,"hot"),(11,"hot"),(12,"rock")] { assert_eq!(terrain(n),want); } }