diff --git a/src/stores.rs b/src/stores.rs
index a062a61..8e98fed 100644
--- a/src/stores.rs
+++ b/src/stores.rs
@@ -38,25 +38,10 @@
 
 use crate::bench::Benchmark;
 use crate::*;
-use ahash::AHasher;
 use hashbrown::HashMap;
 use log::debug;
-use std::hash::Hasher;
 use toml::Table;
 
-pub fn hash(key: &[u8]) -> u64 {
-    let mut hasher = AHasher::default();
-    hasher.write(key);
-    u64::from(hasher.finish())
-}
-
-pub fn find_shard(key: &[u8], nr_shards: usize) -> usize {
-    let mut hasher = AHasher::default();
-    hasher.write(key);
-    let hash = u64::from(hasher.finish());
-    usize::try_from(hash).unwrap() % nr_shards
-}
-
 /// A unified enum for a created key-value store that is ready to run.
 pub enum BenchKVMap {
     Regular(Box<dyn KVMap>),
diff --git a/src/stores/hashmap.rs b/src/stores/hashmap.rs
index 489037c..1719fde 100644
--- a/src/stores/hashmap.rs
+++ b/src/stores/hashmap.rs
@@ -21,12 +21,27 @@
 //!
 //! This store is [`KVMap`].
 
-use crate::stores::*;
+use crate::stores::{BenchKVMap, Registry};
+use crate::*;
 use ::hashbrown::HashMap;
+use ahash::AHasher;
 use parking_lot::{Mutex, RwLock};
 use serde::Deserialize;
+use std::hash::Hasher;
 use std::sync::Arc;
 
+/// Calculate the [`u64`] hash value of a given key using [`AHasher`].
+pub fn hash(key: &[u8]) -> u64 {
+    let mut hasher = AHasher::default();
+    hasher.write(key);
+    u64::from(hasher.finish())
+}
+
+pub fn shard(key: &[u8], nr_shards: usize) -> usize {
+    let hash = hash(key);
+    usize::try_from(hash).unwrap() % nr_shards
+}
+
 /// A wrapper around raw [`HashMap`] with variable-sized keys and values.
 ///
 /// It is used as the building block of other types. Note that this is not [`KVMap`].
@@ -68,12 +83,12 @@ impl KVMap for MutexHashMap {
 
 impl KVMapHandle for MutexHashMap {
     fn set(&mut self, key: &[u8], value: &[u8]) {
-        let sid = find_shard(key, self.nr_shards);
+        let sid = shard(key, self.nr_shards);
         self.shards[sid].lock().insert(key.into(), value.into());
     }
 
     fn get(&mut self, key: &[u8]) -> Option<Box<[u8]>> {
-        let sid = find_shard(key, self.nr_shards);
+        let sid = shard(key, self.nr_shards);
         match self.shards[sid].lock().get(key) {
             Some(v) => Some(v.clone()),
             None => None,
@@ -81,7 +96,7 @@ impl KVMapHandle for MutexHashMap {
     }
 
     fn delete(&mut self, key: &[u8]) {
-        let sid = find_shard(key, self.nr_shards);
+        let sid = shard(key, self.nr_shards);
         self.shards[sid].lock().remove(key);
     }
 }
@@ -130,12 +145,12 @@ impl KVMap for RwLockHashMap {
 
 impl KVMapHandle for RwLockHashMap {
     fn set(&mut self, key: &[u8], value: &[u8]) {
-        let sid = find_shard(key, self.nr_shards);
+        let sid = shard(key, self.nr_shards);
         self.shards[sid].write().insert(key.into(), value.into());
     }
 
     fn get(&mut self, key: &[u8]) -> Option<Box<[u8]>> {
-        let sid = find_shard(key, self.nr_shards);
+        let sid = shard(key, self.nr_shards);
         match self.shards[sid].read().get(key) {
             Some(v) => Some(v.clone()),
             None => None,
@@ -143,7 +158,7 @@ impl KVMapHandle for RwLockHashMap {
     }
 
     fn delete(&mut self, key: &[u8]) {
-        let sid = find_shard(key, self.nr_shards);
+        let sid = shard(key, self.nr_shards);
         self.shards[sid].write().remove(key);
     }
 }
diff --git a/src/thread.rs b/src/thread.rs
index de61924..ceebc9b 100644
--- a/src/thread.rs
+++ b/src/thread.rs
@@ -4,8 +4,8 @@
 //!
 //! A key-value store is generally passive. However, some store may act like a server with
 //! active threads. In that case, one may employ its own implementation of spawn-join. If that is
-//! the case, their join handle (like `[std::thread::JoinHandle`]) should implement the
-//! [`JoinHandle`] trait and the spawn struct needs to implement `[Spawn]`.
+//! the case, their join handle (like [`std::thread::JoinHandle`]) should implement the
+//! [`JoinHandle`] trait and the spawn struct needs to implement [`Spawn]`.
 //!
 //! Note that for simplicity, the function spawn is generic over should not have a return value. So
 //! it is with the [`JoinHandle`]. Because the purpose is not general spawn-join but solely for