How to run a sample example?

I am unable to execute this test:

use hash_db::Hasher;
use reference_trie::{RefTrieDBMut, RefTrieDB};
use trie_db::DBValue;
use keccak_hasher::KeccakHasher;
use memory_db::*;

fn main() {
    let mut memdb = MemoryDB::<KeccakHasher, HashKey<_>, _>::default();
    let mut root = Default::default();
    RefTrieDBMut::new(&mut memdb, &mut root).insert(b"foo", b"bar").unwrap();
    let t = RefTrieDB::new(&memdb, &root);
    assert!(t.contains(b"foo").unwrap());
    assert_eq!(t.get(b"foo").unwrap().unwrap(), b"bar".to_vec());
}

But I get this error:

 --> src/main.rs:10:19
   |
10 |     RefTrieDBMut::new(&mut memdb, &mut root).insert(b"foo", b"bar").unwrap();
   |                   ^^^ function or associated item not found in `trie_db::triedbmut::TrieDBMut<'_, ExtensionLayout>`

And Indeed trie_db::triedbmut::TrieDBMut doesn't have a new method. Any help?

Start with the failing call in src/main.rs and inspect the crate versions and APIs for RefTrieDBMut and RefTrieDB. Compare the example's imports and constructor usage with the currently exposed API. Done means the sample compiles and its assertions pass, or the example documents the correct way to run it.