You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test.rs
    path of file: ./repos/holochain/crates/holochain_types/src/chain
    
    the code of the file until where you have to start completion: use holo_hash::*;
use std::collections::HashMap;
use std::ops::Range;
use test_case::test_case;

use crate::test_utils::chain::*;

use super::*;

type TestHash = <TestChainI
    
fn hash_to_seq(hashes: &[u32]) -> impl FnMut(&ActionHash) -> Option<u32> {
    let map = hashes
        .iter()
        .map(|i| {
            let hash = hash_from_u32(*i);
            (hash, *i)
        })
        .collect::<HashMap<_, _>>();
    move |hash| map.get(hash).copied()
}