diff --git a/shared/src/ledger/storage_api/collections/lazy_hashmap.rs b/shared/src/ledger/storage_api/collections/lazy_hashmap.rs
new file mode 100644
index 00000000000..405262b33d0
--- /dev/null
+++ b/shared/src/ledger/storage_api/collections/lazy_hashmap.rs
@@ -0,0 +1,171 @@
+//! Lazy hash map
+
+use std::marker::PhantomData;
+
+use borsh::{BorshDeserialize, BorshSerialize};
+
+use super::super::Result;
+use super::hasher::hash_for_storage_key;
+use crate::ledger::storage_api::{self, StorageRead, StorageWrite};
+use crate::types::storage;
+
+/// Subkey corresponding to the data elements of the LazyMap
+pub const DATA_SUBKEY: &str = "data";
+
+/// LazyHashmap ! fill in !
+pub struct LazyHashMap<K, V> {
+    key: storage::Key,
+    phantom_k: PhantomData<K>,
+    phantom_v: PhantomData<V>,
+}
+
+/// Struct to hold a key-value pair
+#[derive(Debug, BorshSerialize, BorshDeserialize)]
+struct KeyVal<K, V> {
+    key: K,
+    val: V,
+}
+
+impl<K, V> LazyMap<K, V>
+where
+    K: BorshDeserialize + BorshSerialize,
+    V: BorshDeserialize + BorshSerialize,
+{
+    /// Create or use an existing map with the given storage `key`.
+    pub fn new(key: storage::Key) -> Self {
+        Self {
+            key,
+            phantom_k: PhantomData,
+            phantom_v: PhantomData,
+        }
+    }
+
+    /// Inserts a key-value pair into the map.
+    ///
+    /// If the map did not have this key present, `None` is returned.
+    /// If the map did have this key present, the value is updated, and the old
+    /// value is returned. Unlike in `std::collection::HashMap`, the key is also
+    /// updated; this matters for types that can be `==` without being
+    /// identical.
+    pub fn insert<S>(
+        &self,
+        storage: &mut S,
+        key: K,
+        val: V,
+    ) -> Result<Option<V>>
+    where
+        S: StorageWrite + StorageRead,
+    {
+        let previous = self.get(storage, &key)?;
+
+        let data_key = self.get_data_key(&key);
+        Self::write_key_val(storage, &data_key, key, val)?;
+
+        Ok(previous)
+    }
+
+    /// Removes a key from the map, returning the value at the key if the key
+    /// was previously in the map.
+    pub fn remove<S>(&self, storage: &mut S, key: &K) -> Result<Option<V>>
+    where
+        S: StorageWrite + StorageRead,
+    {
+        let value = self.get(storage, key)?;
+
+        let data_key = self.get_data_key(key);
+        storage.delete(&data_key)?;
+
+        Ok(value)
+    }
+
+    /// Returns the value corresponding to the key, if any.
+    pub fn get(
+        &self,
+        storage: &impl StorageRead,
+        key: &K,
+    ) -> Result<Option<V>> {
+        let res = self.get_key_val(storage, key)?;
+        Ok(res.map(|elem| elem.1))
+    }
+
+    /// Returns the key-value corresponding to the key, if any.
+    pub fn get_key_val(
+        &self,
+        storage: &impl StorageRead,
+        key: &K,
+    ) -> Result<Option<(K, V)>> {
+        let data_key = self.get_data_key(key);
+        Self::read_key_val(storage, &data_key)
+    }
+
+    /// Returns the key-value corresponding to the given hash of a key, if any.
+    pub fn get_key_val_by_hash(
+        &self,
+        storage: &impl StorageRead,
+        key_hash: &str,
+    ) -> Result<Option<(K, V)>> {
+        let data_key =
+            self.get_data_prefix().push(&key_hash.to_string()).unwrap();
+        Self::read_key_val(storage, &data_key)
+    }
+
+    /// An iterator visiting all key-value elements. The iterator element type
+    /// is `Result<(K, V)>`, because iterator's call to `next` may fail with
+    /// e.g. out of gas or data decoding error.
+    ///
+    /// Note that this function shouldn't be used in transactions and VPs code
+    /// on unbounded sets to avoid gas usage increasing with the length of the
+    /// map.
+    pub fn iter<'a>(
+        &self,
+        storage: &'a impl StorageRead,
+    ) -> Result<impl Iterator<Item = Result<(K, V)>> + 'a> {
+        let iter = storage.iter_prefix(&self.get_data_prefix())?;
+        let iter = itertools::unfold(iter, |iter| {
+            match storage.iter_next(iter) {
+                Ok(Some((_key, value))) => {
+                    match KeyVal::<K, V>::try_from_slice(&value[..]) {
+                        Ok(KeyVal { key, val }) => Some(Ok((key, val))),
+                        Err(err) => Some(Err(storage_api::Error::new(err))),
+                    }
+                }
+                Ok(None) => None,
+                Err(err) => {
+                    // Propagate errors into Iterator's Item
+                    Some(Err(err))
+                }
+            }
+        });
+        Ok(iter)
+    }
+
+    /// Reads a key-value from storage
+    fn read_key_val(
+        storage: &impl StorageRead,
+        storage_key: &storage::Key,
+    ) -> Result<Option<(K, V)>> {
+        let res = storage.read(storage_key)?;
+        Ok(res.map(|KeyVal { key, val }| (key, val)))
+    }
+
+    /// Write a key-value into storage
+    fn write_key_val(
+        storage: &mut impl StorageWrite,
+        storage_key: &storage::Key,
+        key: K,
+        val: V,
+    ) -> Result<()> {
+        storage.write(storage_key, KeyVal { key, val })
+    }
+
+    /// Get the prefix of set's elements storage
+    fn get_data_prefix(&self) -> storage::Key {
+        self.key.push(&DATA_SUBKEY.to_owned()).unwrap()
+    }
+
+    /// Get the sub-key of a given element
+    fn get_data_key(&self, key: &K) -> storage::Key {
+        let hash_str = hash_for_storage_key(key);
+        self.get_data_prefix().push(&hash_str).unwrap()
+    }
+}
diff --git a/shared/src/ledger/storage_api/collections/lazy_map.rs b/shared/src/ledger/storage_api/collections/lazy_map.rs
index 25b4cd4d5df..01af3c5a42d 100644
--- a/shared/src/ledger/storage_api/collections/lazy_map.rs
+++ b/shared/src/ledger/storage_api/collections/lazy_map.rs
@@ -1,11 +1,11 @@
-//! Lazy map
+//! Lazy hash map
 
+use std::fmt::Display;
 use std::marker::PhantomData;
 
 use borsh::{BorshDeserialize, BorshSerialize};
 
 use super::super::Result;
-use super::hasher::hash_for_storage_key;
 use crate::ledger::storage_api::{self, StorageRead, StorageWrite};
 use crate::types::storage;
 
@@ -15,32 +15,29 @@ pub const DATA_SUBKEY: &str = "data";
 /// LazyMap ! fill in !
 pub struct LazyMap<K, V> {
     key: storage::Key,
-    phantom_h: PhantomData<K>,
-    phantom_t: PhantomData<V>,
-}
-
-#[derive(Debug, BorshSerialize, BorshDeserialize)]
-struct KeyVal<K, V> {
-    key: K,
-    val: V,
+    phantom_k: PhantomData<K>,
+    phantom_v: PhantomData<V>,
 }
 
 impl<K, V> LazyMap<K, V>
 where
-    K: BorshDeserialize + BorshSerialize,
+    K: BorshDeserialize + BorshSerialize + Display,
     V: BorshDeserialize + BorshSerialize,
 {
     /// Create or use an existing map with the given storage `key`.
     pub fn new(key: storage::Key) -> Self {
         Self {
             key,
-            phantom_h: PhantomData,
-            phantom_t: PhantomData,
+            phantom_k: PhantomData,
+            phantom_v: PhantomData,
         }
     }
 
     /// Inserts a key-value pair into the map.
     ///
+    /// The full storage key identifies the key in the pair, while the value is
+    /// held within the storage key.
+    ///
     /// If the map did not have this key present, `None` is returned.
     /// If the map did have this key present, the value is updated, and the old
     /// value is returned. Unlike in `std::collection::HashMap`, the key is also
@@ -58,7 +55,7 @@ where
         let previous = self.get(storage, &key)?;
 
         let data_key = self.get_data_key(&key);
-        Self::write_key_val(storage, &data_key, key, val)?;
+        Self::write_key_val(storage, &data_key, val)?;
 
         Ok(previous)
     }
@@ -83,31 +80,10 @@ where
         storage: &impl StorageRead,
         key: &K,
     ) -> Result<Option<V>> {
-        let res = self.get_key_val(storage, key)?;
-        Ok(res.map(|elem| elem.1))
-    }
-
-    /// Returns the key-value corresponding to the key, if any.
-    pub fn get_key_val(
-        &self,
-        storage: &impl StorageRead,
-        key: &K,
-    ) -> Result<Option<(K, V)>> {
         let data_key = self.get_data_key(key);
         Self::read_key_val(storage, &data_key)
     }
 
-    /// Returns the key-value corresponding to the given hash of a key, if any.
-    pub fn get_key_val_by_hash(
-        &self,
-        storage: &impl StorageRead,
-        key_hash: &str,
-    ) -> Result<Option<(K, V)>> {
-        let data_key =
-            self.get_data_prefix().push(&key_hash.to_string()).unwrap();
-        Self::read_key_val(storage, &data_key)
-    }
-
     /// An iterator visiting all key-value elements. The iterator element type
     /// is `Result<(K, V)>`, because iterator's call to `next` may fail with
     /// e.g. out of gas or data decoding error.
@@ -118,13 +94,13 @@ where
     pub fn iter<'a>(
         &self,
         storage: &'a impl StorageRead,
-    ) -> Result<impl Iterator<Item = Result<(K, V)>> + 'a> {
+    ) -> Result<impl Iterator<Item = Result<V>> + 'a> {
         let iter = storage.iter_prefix(&self.get_data_prefix())?;
         let iter = itertools::unfold(iter, |iter| {
             match storage.iter_next(iter) {
                 Ok(Some((_key, value))) => {
-                    match KeyVal::<K, V>::try_from_slice(&value[..]) {
-                        Ok(KeyVal { key, val }) => Some(Ok((key, val))),
+                    match V::try_from_slice(&value[..]) {
+                        Ok(decoded_value) => Some(Ok(decoded_value)),
                         Err(err) => Some(Err(storage_api::Error::new(err))),
                     }
                 }
@@ -138,23 +114,22 @@ where
         Ok(iter)
     }
 
-    /// Reads a key-value from storage
+    /// Reads a value from storage
     fn read_key_val(
         storage: &impl StorageRead,
         storage_key: &storage::Key,
-    ) -> Result<Option<(K, V)>> {
+    ) -> Result<Option<V>> {
         let res = storage.read(storage_key)?;
-        Ok(res.map(|KeyVal { key, val }| (key, val)))
+        Ok(res)
     }
 
-    /// Write a key-value into storage
+    /// Write a value into storage
     fn write_key_val(
         storage: &mut impl StorageWrite,
         storage_key: &storage::Key,
-        key: K,
         val: V,
     ) -> Result<()> {
-        storage.write(storage_key, KeyVal { key, val })
+        storage.write(storage_key, val)
     }
 
     /// Get the prefix of set's elements storage
@@ -164,7 +139,6 @@ where
 
     /// Get the sub-key of a given element
     fn get_data_key(&self, key: &K) -> storage::Key {
-        let hash_str = hash_for_storage_key(key);
-        self.get_data_prefix().push(&hash_str).unwrap()
+        self.get_data_prefix().push(&key.to_string()).unwrap()
     }
 }