#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::collections::HashMap;
use std::hash::{BuildHasherDefault, Hasher};
#[derive(Default)]
struct MyHasher;
impl Hasher for MyHasher {
    fn write(&mut self, bytes: &[u8]) {
        unimplemented!()
    }
    fn finish(&self) -> u64 {
        unimplemented!()
    }
}
type MyBuildHasher = BuildHasherDefault<MyHasher>;
fn main() {
    let hash_map = HashMap::<u32, u32, MyBuildHasher>::default();
}