diff --git a/README.rst b/README.rst
index 61cff790..264553e5 100644
--- a/README.rst
+++ b/README.rst
@@ -109,19 +109,9 @@ your application objects when you apply dependency injection principle:
 .. code-block:: python
 
     from dependency_injector import containers, providers
+    from unittest import mock
 
-
-    class ApiClient:
-
-        def __init__(self, api_key: str, timeout: int):
-            self.api_key = api_key
-            self.timeout = timeout
-
-
-    class Service:
-
-        def __init__(self, api_client: ApiClient):
-            self.api_client = api_client
+    from .example_di import ApiClient, Service
 
 
     class Container(containers.DeclarativeContainer):
@@ -145,9 +135,12 @@ your application objects when you apply dependency injection principle:
         container.config.from_yaml('config.yml')
 
         service = container.service()
-
         assert isinstance(service.api_client, ApiClient)
 
+        with container.api_client.override(mock.Mock()):
+            service = container.service()
+            assert isinstance(service.api_client, mock.Mock)
+
 `More examples <https://github.com/ets-labs/python-dependency-injector/tree/master/examples>`_
 
 Installation
diff --git a/examples/di_demo2/demo.py b/examples/di_demo2/demo.py
index 886b0de1..d0e2cb9a 100644
--- a/examples/di_demo2/demo.py
+++ b/examples/di_demo2/demo.py
@@ -1,18 +1,7 @@
 from dependency_injector import containers, providers
 from unittest import mock
 
-
-class ApiClient:
-
-    def __init__(self, api_key: str, timeout: int):
-        self.api_key = api_key
-        self.timeout = timeout
-
-
-class Service:
-
-    def __init__(self, api_client: ApiClient):
-        self.api_client = api_client
+from .example_di import ApiClient, Service
 
 
 class Container(containers.DeclarativeContainer):
@@ -41,4 +30,3 @@ if __name__ == '__main__':
     with container.api_client.override(mock.Mock()):
         service = container.service()
         assert isinstance(service.api_client, mock.Mock)
-
diff --git a/examples/di_demo2/example_di.py b/examples/di_demo2/example_di.py
new file mode 100644
index 00000000..2a4bb423
--- /dev/null
+++ b/examples/di_demo2/example_di.py
@@ -0,0 +1,13 @@
+
+
+class ApiClient:
+
+    def __init__(self, api_key: str, timeout: int):
+        self.api_key = api_key
+        self.timeout = timeout
+
+
+class Service:
+
+    def __init__(self, api_client: ApiClient):
+        self.api_client = api_client
diff --git a/examples/di_demo2/example_no_di.py b/examples/di_demo2/example_no_di.py
new file mode 100644
index 00000000..28ca034e
--- /dev/null
+++ b/examples/di_demo2/example_no_di.py
@@ -0,0 +1,14 @@
+import os
+
+
+class ApiClient:
+
+    def __init__(self):
+        self.api_key = os.getenv('API_KEY')
+        self.timeout = os.getenv('TIMEOUT')
+
+
+class Service:
+
+    def __init__(self):
+        self.api_client = ApiClient()