fs::create_dir_all("target/zerocopy.mdb")?;
let env = EnvOpenOptions::new().open("target/zerocopy.mdb")?;

// we will open the default unamed database
let db: Database<Str, OwnedType<i32>> = env.create_database(None)?;

// opening a write transaction
let mut wtxn = env.write_txn()?;
db.put(&mut wtxn, "seven", &7)?;
db.put(&mut wtxn, "zero", &0)?;
db.put(&mut wtxn, "five", &5)?;
db.put(&mut wtxn, "three", &3)?;
wtxn.commit()?;

// opening a read transaction
// to check if those values are now available
let mut rtxn = env.read_txn()?;

let ret = db.get(&rtxn, "zero")?;
assert_eq!(ret, Some(0));

let ret = db.get(&rtxn, "five")?;
assert_eq!(ret, Some(5));