Add example usage

documentation/specification.adoc

@@ -324,9 +324,6 @@ pub enum AccumulatorError {
 impl Accumulator<ID>
 where:
   ID: Id {
-    // Increase the point in time to start a new batch of changes and clear the previous one
-    fn new_block(&mut self, block_number: u64);
-
     // Ask for the read of a key (should return also with modifications that are not applied to the database yet)
     fn get(&self, key: &[u8]) -> Result<TrieValue, AccumulatorError>;
 
@@ -349,7 +346,7 @@ where:
     fn goto(&mut self, id: ID) -> Result<(), AccumulatorError>;
 
     // Apply all the changes to the database and create a trielog (and a snapshot if we are at X point in time) with all the changes and clear them.
-    fn commit(&mut self);
+    fn commit(&mut self, id: ID);
 }
 ----
 
@@ -430,7 +427,69 @@ This interface should be the only interface used by the caller to have a compreh
 
 ==== Definition
 
-For now, the interface is the same as the one of the accumulator.
+[source,rust]
+----
+pub trait BonsaiStorage<'a, ID>
+where: 
+  ID: Id {
+    // Create a new bonsai storage instance
+    fn new(db: &'a mut KeyValueDB<DB, ID>, root: &'a mut BonsaiTrieHash) -> Self;
+
+    // Insert a new key/value in the trie
+    fn insert(&mut self, key: &[u8], value: &[u8]);
+
+    // Remove a key/value in the trie
+    fn remove(&mut self, key: &[u8]);
+
+    // Commit all the changes to the trie
+    fn commit(&mut self, id: ID);
+
+    // Get a value in the trie
+    fn get(&self, key: &[u8]);
+
+    // Go to a specific point in time, if possible, using trie logs and snapshots.
+    fn go_to(&mut self, requested_id: ID);
+    
+    // Get the root hash of the trie
+    fn root(&self) -> Hash;
+}
+----
+
+==== Usage example
+
+For example you will be able to use the interface like this:
+
+[source,rust]
+----
+fn main() {
+  let mut db = KeyValueDB::<RocksDB, BasicId>::new(RocksDB::new("./rocksdb")); // add empty node
+  let mut root = BonsaiTrieHash::default();
+  let mut bonsai_storage = BonsaiStorage::new(&mut db, &mut root);
+  let mut id_builder = BasicIdBuilder::new();
+  bonsai_storage.insert(&[1, 2, 3, 4, 5, 6], &[4, 5, 6]);
+  bonsai_storage.insert(&[1, 2, 3, 4, 5, 7], &[4, 5, 8]);
+  bonsai_storage.commit(id_builder.new_id());
+  bonsai_storage.insert(&[1, 2, 2], &[7, 5, 6]);
+  let go_to_id = id_builder.new_id();
+  bonsai_storage.commit(go_to_id);
+  bonsai_storage.remove(&[1, 2, 2]);
+  bonsai_storage.commit(id_builder.new_id());
+  println!("root: {:#?}", bonsai_storage.root());
+  println!(
+      "value: {:#?}",
+      bonsai_storage.get(&[1, 2, 3, 4, 5, 6]).unwrap()
+  );
+  bonsai_storage.go_to(go_to_id).unwrap();
+  println!("root: {:#?}", bonsai_storage.root());
+  println!("value: {:#?}", bonsai_storage.get(&[1, 2, 2]).unwrap());
+}
+----
+
+==== Disclaimer
+
+All the interfaces above are subjects to little adaptations changes while making the implementation.
+
+Every methods are shown in a trait here to illustrate them in this document but if genericity is not needed, we will use a struct with methods directly.
 
 === E2E & Benchmarks