more on usage

docs/source/usage.rst

@@ -24,11 +24,34 @@ Basic functionality
 
     import pathlib
     from ptvp35 import DbFactory, KVJson
-    
+
     async def main():
         async with DbFactory(pathlib.Path('example.db', kvfactory=KVJson())) as connection:
             await _main(connection)
 
+Different ways to get/set a value:
+
+.. code-block:: python3
+
+    from ptvp35 import DbConnection
+
+    async def _main(connection: DbConnection):
+        value0 = connection.get('increment-0', 0)
+        await connection.set('increment-0', value0 + 1)
+
+        value1 = connection.get('increment-1', 0)
+        connection.set_nowait('increment-1', value1 + 1)
+        await connection.commit()
+
+        async with connection.transaction() as transaction:
+            value2 = transaction.get('increment-2', 0)
+            transaction.set_nowait('increment-2', value2 + 1)
+
+        async with connection.transaction() as transaction:
+            value3 = transaction.get('increment-3', 0)
+            transaction.set_nowait('increment-3', value3 + 1)
+            await transaction.commit()
+
 .. autoclass:: ptvp35.DbConnection
 
     .. automethod:: get

ptvp35/__init__.py

@@ -524,7 +524,7 @@ note: unstable signature."""
     def submit_transaction(self, delta: dict, future: asyncio.Future | None, /) -> None:
         """not implemented.
 low-level API.
-note: unstable signature."""
+note: unstable (undefined) signature."""
         raise NotImplementedError
 
     async def commit(self, /) -> None: