diff --git a/docs/examples-other/chained-factories.rst b/docs/examples-other/chained-factories.rst
new file mode 100644
index 00000000..0bec024e
--- /dev/null
+++ b/docs/examples-other/chained-factories.rst
@@ -0,0 +1,68 @@
+Chained Factories pattern
+=========================
+
+This example demonstrates "Chained Factories" pattern.
+
+The idea of the pattern is in wrapping ``Factory`` into another ``Factory`` that adds
+additional arguments.
+
+.. code-block:: python
+
+   base_factory = providers.Factory(
+       SomeClass,
+       base_argument=1,
+   )
+
+   concrete_factory = providers.Factory(
+       base_factory,
+       extra_argument=2,
+   )
+
+
+   if __name__ == '__main__':
+       instance = concrete_factory()
+       # Same as: # instance = SomeClass(base_argument=1, extra_argument=2)
+
+Sample code
+-----------
+
+Listing of the pattern example:
+
+.. literalinclude:: ../../examples/miniapps/factory-patterns/chained_factories.py
+   :language: python
+
+Arguments priority
+------------------
+
+Passing of the arguments works the same way like for any other :ref:`factory-provider`.
+
+.. code-block:: python
+
+   # 1. Keyword arguments of upper level factory are added to lower level factory
+   chained_dict_factory = providers.Factory(
+       providers.Factory(dict, arg1=1),
+       arg2=2,
+   )
+   print(chained_dict_factory())  # prints: {'arg1': 1, 'arg2': 2}
+
+   # 2. Keyword arguments of upper level factory have priority
+   chained_dict_factory = providers.Factory(
+       providers.Factory(dict, arg1=1),
+       arg1=2,
+   )
+   print(chained_dict_factory())  # prints: {'arg1': 2}
+
+   # 3. Keyword arguments provided from context have the most priority
+   chained_dict_factory = providers.Factory(
+       providers.Factory(dict, arg1=1),
+       arg1=2,
+   )
+   print(chained_dict_factory(arg1=3))  # prints: {'arg1': 3}
+
+
+Credits
+-------
+
+The "Chained Factories" pattern was suggested by the ``Dependency Injector`` users.
+
+.. disqus::
diff --git a/docs/examples-other/chained_factories.rst b/docs/examples-other/chained_factories.rst
deleted file mode 100644
index 6d20bc7a..00000000
--- a/docs/examples-other/chained_factories.rst
+++ /dev/null
@@ -1,21 +0,0 @@
-Chained Factories pattern
-=========================
-
-This example demonstrate implementation of "Chained Factories" pattern.
-Main idea of this pattern is about wrapping :py:class:`Factory` into
-another :py:class:`Factory` that mix additional arguments or keyword
-arguments to a wrapped one.
-
-Listing of ``data.py``, demonstrates sample classes structure:
-
-.. literalinclude:: ../../examples/miniapps/factory_patterns/data.py
-   :language: python
-
-Listing of ``chained_factories.py``, demonstrates "Chained Factories"
-pattern and provide some explanation:
-
-.. literalinclude:: ../../examples/miniapps/factory_patterns/chained_factories.py
-   :language: python
-
-
-.. disqus::
diff --git a/docs/examples-other/factory-of-factories.rst b/docs/examples-other/factory-of-factories.rst
new file mode 100644
index 00000000..6cc71aa3
--- /dev/null
+++ b/docs/examples-other/factory-of-factories.rst
@@ -0,0 +1,74 @@
+Factory of Factories pattern
+============================
+
+This example demonstrates "Factory of Factories" pattern.
+
+The idea of the pattern is in creating a ``Factory`` that creates another ``Factory`` and adds
+additional arguments.
+
+.. code-block:: python
+
+   base_factory = providers.Factory(
+       providers.Factory
+       SomeClass,
+       base_argument=1,
+   )
+
+   concrete_factory = providers.Factory(
+       OtherClass,
+       instance=base_factory(extra_argument=1),
+   )
+
+
+   if __name__ == '__main__':
+       instance = concrete_factory()
+       # Same as: # instance = SomeClass(base_argument=1, extra_argument=2)
+
+Sample code
+-----------
+
+Listing of the pattern example:
+
+.. literalinclude:: ../../examples/miniapps/factory-patterns/factory_of_factories.py
+   :language: python
+
+Arguments priority
+------------------
+
+Passing of the arguments works the same way like for any other :ref:`factory-provider`.
+
+.. code-block:: python
+
+   # 1. Keyword arguments of upper level factory are added to lower level factory
+   factory_of_dict_factories = providers.Factory(
+       providers.Factory,
+       dict,
+       arg1=1,
+   )
+   dict_factory = factory_of_dict_factories(arg2=2)
+   print(dict_factory())  # prints: {'arg1': 1, 'arg2': 2}
+
+   # 2. Keyword arguments of upper level factory have priority
+   factory_of_dict_factories = providers.Factory(
+       providers.Factory,
+       dict,
+       arg1=1,
+   )
+   dict_factory = factory_of_dict_factories(arg1=2)
+   print(dict_factory())  # prints: {'arg1': 2}
+
+   # 3. Keyword arguments provided from context have the most priority
+   factory_of_dict_factories = providers.Factory(
+       providers.Factory,
+       dict,
+       arg1=1,
+   )
+   dict_factory = factory_of_dict_factories(arg1=2)
+   print(dict_factory(arg1=3))  # prints: {'arg1': 3}
+
+Credits
+-------
+
+The "Factory of Factories" pattern was suggested by the ``Dependency Injector`` users.
+
+.. disqus::
diff --git a/docs/examples-other/factory_of_factories.rst b/docs/examples-other/factory_of_factories.rst
deleted file mode 100644
index d3ef157b..00000000
--- a/docs/examples-other/factory_of_factories.rst
+++ /dev/null
@@ -1,20 +0,0 @@
-Factory of Factories pattern
-============================
-
-This example demonstrate implementation of "Factory of Factories" pattern.
-Main idea of this pattern is about creation of a :py:class:`Factory` that
-creates another :py:class:`Factory` and mix additional arguments to it.
-
-Listing of ``data.py``, demonstrates sample classes structure:
-
-.. literalinclude:: ../../examples/miniapps/factory_patterns/data.py
-   :language: python
-
-Listing of ``factory_of_factories.py``, demonstrates "Chained Factories"
-pattern and provide some explanation:
-
-.. literalinclude:: ../../examples/miniapps/factory_patterns/factory_of_factories.py
-   :language: python
-
-
-.. disqus::
diff --git a/docs/examples-other/index.rst b/docs/examples-other/index.rst
index 8b082fa8..023e60ec 100644
--- a/docs/examples-other/index.rst
+++ b/docs/examples-other/index.rst
@@ -2,18 +2,16 @@ Other examples
 ==============
 
 .. meta::
-   :keywords: Python,DI,Dependency injection,IoC,Inversion of Control
-   :description: Current section of documentation is designed to provide 
-                 several example mini applications that are built on the top 
-                 of inversion of control principle and powered by 
-                 "Dependency Injector" framework.
+   :keywords: Python,Dependency Injection,Inversion of Control,Container,Example,Application,
+              Framework
+   :description: This sections contains assorted Dependency Injector examples.
 
 This sections contains assorted ``Dependency Injector`` examples.
 
 ..  toctree::
     :maxdepth: 2
 
-    use_cases_miniapp
-    password_hashing_miniapp
-    chained_factories
-    factory_of_factories
+    use-cases
+    password-hashing
+    chained-factories
+    factory-of-factories
diff --git a/docs/examples-other/password-hashing.rst b/docs/examples-other/password-hashing.rst
new file mode 100644
index 00000000..d4d0af39
--- /dev/null
+++ b/docs/examples-other/password-hashing.rst
@@ -0,0 +1,30 @@
+Password hashing example
+========================
+
+.. meta::
+   :keywords: Python,Dependency Injection,Inversion of Control,Container,Example,Application,
+              Framework,Callable
+   :description: This example demonstrates a usage of the Callable provider.
+
+This example demonstrates an injection of the ``Callable`` provider.
+
+The source code is available on the `Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/password-hashing>`_.
+
+Sample code
+-----------
+
+Listing of the pattern example:
+
+.. literalinclude:: ../../examples/miniapps/password-hashing/example.py
+   :language: python
+
+Run the example
+---------------
+
+Instructions for running:
+
+.. code-block:: bash
+
+    python example.py
+
+.. disqus::
diff --git a/docs/examples-other/password_hashing_miniapp.rst b/docs/examples-other/password_hashing_miniapp.rst
deleted file mode 100644
index 21177545..00000000
--- a/docs/examples-other/password_hashing_miniapp.rst
+++ /dev/null
@@ -1,18 +0,0 @@
-Dependency injection and password hashing in Python
-===================================================
-
-Small example that demonstrates using of dependency injection for user
-password hashing.
-
-Instructions for running:
-
-.. code-block:: bash
-
-    python example.py
-
-Listing of ``example.py``:
-
-.. literalinclude:: ../../examples/miniapps/password_hashing/example.py
-   :language: python
-
-.. disqus::
diff --git a/docs/examples-other/use-cases.rst b/docs/examples-other/use-cases.rst
new file mode 100644
index 00000000..9f191e39
--- /dev/null
+++ b/docs/examples-other/use-cases.rst
@@ -0,0 +1,74 @@
+Use cases example
+=================
+
+.. meta::
+   :keywords: Python,Dependency Injection,Inversion of Control,Container,Example,Application,
+              Framework,DependenciesContainer
+   :description: This example demonstrates a usage of the DependenciesContainer provider.
+
+This example demonstrates a usage of the ``DependenciesContainer`` provider.
+
+The source code is available on the `Github <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/decoupled-packages>`_.
+
+Application structure
+---------------------
+
+Example application has next structure:
+
+.. code-block:: bash
+
+
+   ./
+   └── example/
+       ├── __init__.py
+       ├── __main__.py
+       ├── adapters.py
+       ├── containers.py
+       └── usecases.py
+
+Containers
+----------
+
+Listing of the ``example/containers.py``:
+
+.. literalinclude:: ../../examples/miniapps/use-cases/example/containers.py
+   :language: python
+
+Main module
+-----------
+
+Listing of the ``example/__main__.py``:
+
+.. literalinclude:: ../../examples/miniapps/use-cases/example/__main__.py
+   :language: python
+
+
+Run the application
+-------------------
+
+Instructions for running in the "test" mode:
+
+.. code-block:: bash
+
+    python run.py test example@example.com
+
+Instructions for running in the "prod" mode:
+
+.. code-block:: bash
+
+    python run.py prod example@example.com
+
+Adapters and use cases
+----------------------
+
+Listing of the ``example/adapters.py``:
+
+.. literalinclude:: ../../examples/miniapps/use-cases/example/adapters.py
+   :language: python
+
+Listing of the ``example/usecases.py``:
+
+.. literalinclude:: ../../examples/miniapps/use-cases/example/usecases.py
+   :language: python
+
+.. disqus::
diff --git a/docs/examples-other/use_cases_miniapp.rst b/docs/examples-other/use_cases_miniapp.rst
deleted file mode 100644
index 03aa7150..00000000
--- a/docs/examples-other/use_cases_miniapp.rst
+++ /dev/null
@@ -1,55 +0,0 @@
-Use cases mini application example
-----------------------------------
-
-.. currentmodule:: dependency_injector.providers
-
-"Use cases" miniapp demonstrate usage of :py:class:`DependenciesContainer` 
-provider.
-
-Example application
-~~~~~~~~~~~~~~~~~~~
-
-"Use cases" mini application has next structure:
-
-.. code-block:: bash
-
-    use_cases/
-        example/               <-- Example package
-            __init__.py
-            adapters.py
-            use_cases.py
-        containers.py          <-- Dependency injection containers
-        run.py                 <-- Entrypoint
-
-
-IoC containers
-~~~~~~~~~~~~~~
-
-Listing of ``use_cases/containers.py``:
-
-.. literalinclude:: ../../examples/miniapps/use_cases/containers.py
-   :language: python
-
-Run application
-~~~~~~~~~~~~~~~
-
-Listing of ``run.py``:
-
-.. literalinclude:: ../../examples/miniapps/use_cases/run.py
-   :language: python
-
-Instructions for running:
-
-.. code-block:: bash
-
-    python run.py prod example@example.com  # Running in "production" environment
-    python run.py test example@example.com  # Running in "testing" environment
-
-Links
-~~~~~
-
-+ `Dependency Injector <https://github.com/ets-labs/python-dependency-injector/>`_
-+ `Full example sources <https://github.com/ets-labs/python-dependency-injector/tree/master/examples/miniapps/use_cases>`_
-
-
-.. disqus::
diff --git a/docs/examples/decoupled-packages.rst b/docs/examples/decoupled-packages.rst
index a030938e..abb4c6ab 100644
--- a/docs/examples/decoupled-packages.rst
+++ b/docs/examples/decoupled-packages.rst
@@ -1,3 +1,5 @@
+.. _decoupled-packages:
+
 Decoupled packages example (multiple containers)
 ================================================
 
diff --git a/docs/introduction/di_in_python.rst b/docs/introduction/di_in_python.rst
index fe56d0ca..7802d7e3 100644
--- a/docs/introduction/di_in_python.rst
+++ b/docs/introduction/di_in_python.rst
@@ -134,6 +134,7 @@ Choose one of the following as a next step:
 - Look at application examples:
     - :ref:`application-single-container`
     - :ref:`application-multiple-containers`
+    - :ref:`decoupled-packages`
 - Pass the tutorials:
     - :ref:`flask-tutorial`
     - :ref:`aiohttp-tutorial`
diff --git a/docs/introduction/what_is_di.rst b/docs/introduction/what_is_di.rst
index 9b9d1248..aa64c07c 100644
--- a/docs/introduction/what_is_di.rst
+++ b/docs/introduction/what_is_di.rst
@@ -178,6 +178,7 @@ Choose one of the following as a next step:
 - Look at application examples:
     - :ref:`application-single-container`
     - :ref:`application-multiple-containers`
+    - :ref:`decoupled-packages`
 - Pass the tutorials:
     - :ref:`flask-tutorial`
     - :ref:`aiohttp-tutorial`
diff --git a/docs/main/changelog.rst b/docs/main/changelog.rst
index 152f925f..ac1f6c85 100644
--- a/docs/main/changelog.rst
+++ b/docs/main/changelog.rst
@@ -7,6 +7,17 @@ that were made in every particular version.
 From version 0.7.6 *Dependency Injector* framework strictly 
 follows `Semantic versioning`_
 
+3.41.0
+------
+- Refactor "use cases" example.
+- Refactor "password hashing" example.
+- Refactor "chained factories" pattern example.
+- Refactor "factory of factories" pattern example.
+- Fix declarative container mypy stub to ``__init__`` to accept not only providers.
+- Refactor main module of the "decoupled packages" example.
+- Delete "api client" example mini app.
+- Delete "mail service" example mini app.
+
 3.40.0
 ------
 - Add "Decoupled packages" example.
diff --git a/examples/miniapps/api_client/api.py b/examples/miniapps/api_client/api.py
deleted file mode 100644
index b876a470..00000000
--- a/examples/miniapps/api_client/api.py
+++ /dev/null
@@ -1,15 +0,0 @@
-"""API client module."""
-
-
-class ApiClient:
-    """Some API client."""
-
-    def __init__(self, host, api_key):
-        """Initialize instance."""
-        self.host = host
-        self.api_key = api_key
-
-    def call(self, operation, data):
-        """Make some network operations."""
-        print('API call [{0}:{1}], method - {2}, data - {3}'.format(
-            self.host, self.api_key, operation, repr(data)))
diff --git a/examples/miniapps/api_client/main.py b/examples/miniapps/api_client/main.py
deleted file mode 100644
index d99979d8..00000000
--- a/examples/miniapps/api_client/main.py
+++ /dev/null
@@ -1,36 +0,0 @@
-"""Main module."""
-
-from dependency_injector import providers
-
-import api
-import models
-
-
-# Creating ApiClient and User providers:
-api_client = providers.Singleton(api.ApiClient,
-                                 host='production.com',
-                                 api_key='PROD_API_KEY')
-user_factory = providers.Factory(models.User,
-                                 api_client=api_client)
-
-
-if __name__ == '__main__':
-    # Creating several users and register them:
-    user1 = user_factory(1)
-    user1.register()
-    # API call [production.com:PROD_API_KEY], method - register, data -
-    # {'id': 1}
-
-    user2 = user_factory(2)
-    user2.register()
-    # API call [production.com:PROD_API_KEY], method - register, data -
-    # {'id': 2}
-
-    # Overriding of ApiClient on dev environment:
-    api_client.override(providers.Singleton(api.ApiClient,
-                                            host='localhost',
-                                            api_key='DEV_API_KEY'))
-
-    user3 = user_factory(3)
-    user3.register()
-    # API call [localhost:DEV_API_KEY], method - register, data - {'id': 3}
diff --git a/examples/miniapps/api_client/models.py b/examples/miniapps/api_client/models.py
deleted file mode 100644
index f8145c02..00000000
--- a/examples/miniapps/api_client/models.py
+++ /dev/null
@@ -1,14 +0,0 @@
-"""Models module."""
-
-
-class User:
-    """User model."""
-
-    def __init__(self, id, api_client):
-        """Initialize instance."""
-        self.id = id
-        self.api_client = api_client
-
-    def register(self):
-        """Register user."""
-        self.api_client.call('register', {'id': self.id})
diff --git a/examples/miniapps/api_client/tests.py b/examples/miniapps/api_client/tests.py
deleted file mode 100644
index c304e6b0..00000000
--- a/examples/miniapps/api_client/tests.py
+++ /dev/null
@@ -1,12 +0,0 @@
-"""Tests module."""
-
-from unittest.mock import Mock
-
-import main
-import api
-
-# Mock ApiClient for testing:
-with main.api_client.override(Mock(api.ApiClient)) as api_client_mock:
-    user = main.user_factory('test')
-    user.register()
-    api_client_mock().call.assert_called_with('register', {'id': 'test'})
diff --git a/examples/miniapps/decoupled-packages/example/__main__.py b/examples/miniapps/decoupled-packages/example/__main__.py
index 2e4e74da..d57cc194 100644
--- a/examples/miniapps/decoupled-packages/example/__main__.py
+++ b/examples/miniapps/decoupled-packages/example/__main__.py
@@ -3,7 +3,7 @@
 from .containers import ApplicationContainer
 
 
-if __name__ == '__main__':
+def main() -> None:
     application = ApplicationContainer()
     application.config.from_ini('config.ini')
 
@@ -22,3 +22,7 @@ if __name__ == '__main__':
     assert aggregation_service.user_repository is user_repository
     assert aggregation_service.photo_repository is photo_repository
     print('Aggregate analytics from user and photo packages')
+
+
+if __name__ == '__main__':
+    main()
diff --git a/examples/miniapps/factory-patterns/chained_factories.py b/examples/miniapps/factory-patterns/chained_factories.py
new file mode 100644
index 00000000..b54da028
--- /dev/null
+++ b/examples/miniapps/factory-patterns/chained_factories.py
@@ -0,0 +1,73 @@
+"""`Chained Factories` pattern."""
+
+from dependency_injector import containers, providers
+
+
+class SqlAlchemyDatabaseService:
+
+    def __init__(self, session, base_class):
+        self.session = session
+        self.base_class = base_class
+
+
+class TokensService:
+
+    def __init__(self, id_generator, database):
+        self.id_generator = id_generator
+        self.database = database
+
+
+class Token:
+    ...
+
+
+class UsersService:
+
+    def __init__(self, id_generator, database):
+        self.id_generator = id_generator
+        self.database = database
+
+
+class User:
+    ...
+
+
+# Sample objects
+session = object()
+id_generator = object()
+
+
+class Container(containers.DeclarativeContainer):
+
+    database = providers.Factory(
+        SqlAlchemyDatabaseService,
+        session=session,
+    )
+
+    token_service = providers.Factory(
+        TokensService,
+        id_generator=id_generator,
+        database=providers.Factory(
+            database,
+            base_class=Token,
+        ),
+    )
+
+    user_service = providers.Factory(
+        UsersService,
+        id_generator=id_generator,
+        database=providers.Factory(
+            database,
+            base_class=User,
+        ),
+    )
+
+
+if __name__ == '__main__':
+    container = Container()
+
+    token_service = container.token_service()
+    assert token_service.database.base_class is Token
+
+    user_service = container.user_service()
+    assert user_service.database.base_class is User
diff --git a/examples/miniapps/factory-patterns/factory_of_factories.py b/examples/miniapps/factory-patterns/factory_of_factories.py
new file mode 100644
index 00000000..664c2c58
--- /dev/null
+++ b/examples/miniapps/factory-patterns/factory_of_factories.py
@@ -0,0 +1,68 @@
+"""`Factory of Factories` pattern."""
+
+from dependency_injector import containers, providers
+
+
+class SqlAlchemyDatabaseService:
+
+    def __init__(self, session, base_class):
+        self.session = session
+        self.base_class = base_class
+
+
+class TokensService:
+
+    def __init__(self, id_generator, database):
+        self.id_generator = id_generator
+        self.database = database
+
+
+class Token:
+    ...
+
+
+class UsersService:
+
+    def __init__(self, id_generator, database):
+        self.id_generator = id_generator
+        self.database = database
+
+
+class User:
+    ...
+
+
+# Sample objects
+session = object()
+id_generator = object()
+
+
+class Container(containers.DeclarativeContainer):
+
+    database_factory = providers.Factory(
+        providers.Factory,
+        SqlAlchemyDatabaseService,
+        session=session,
+    )
+
+    token_service = providers.Factory(
+        TokensService,
+        id_generator=id_generator,
+        database=database_factory(base_class=Token),
+    )
+
+    user_service = providers.Factory(
+        UsersService,
+        id_generator=id_generator,
+        database=database_factory(base_class=User),
+    )
+
+
+if __name__ == '__main__':
+    container = Container()
+
+    token_service = container.token_service()
+    assert token_service.database.base_class is Token
+
+    user_service = container.user_service()
+    assert user_service.database.base_class is User
diff --git a/examples/miniapps/factory_patterns/chained_factories.py b/examples/miniapps/factory_patterns/chained_factories.py
deleted file mode 100644
index 993d1fa2..00000000
--- a/examples/miniapps/factory_patterns/chained_factories.py
+++ /dev/null
@@ -1,59 +0,0 @@
-"""`Chained Factories` pattern."""
-
-from dependency_injector import providers
-
-from data import (
-    id_generator,
-    session,
-    SqlAlchemyDatabaseService,
-    TokensService,
-    Token,
-    UsersService,
-    User,
-)
-
-
-# "Chained Factories" pattern
-
-database = providers.Factory(SqlAlchemyDatabaseService, session=session)
-
-tokens = providers.Factory(
-    TokensService,
-    id_generator=id_generator,
-    database=providers.Factory(database, base_class=Token),
-)
-
-users = providers.Factory(
-    UsersService,
-    id_generator=id_generator,
-    database=providers.Factory(database, base_class=User),
-)
-
-tokens_service = tokens()
-assert tokens_service.database.base_class is Token
-
-users_service = users()
-assert users_service.database.base_class is User
-
-# Explanation & some more examples
-
-# 1. Keyword arguments of upper level factory are added to lower level factory
-chained_dict_factory = providers.Factory(
-    providers.Factory(dict, arg1=1),
-    arg2=2,
-)
-print(chained_dict_factory())  # prints: {'arg1': 1, 'arg2': 2}
-
-# 2. Keyword arguments of upper level factory have priority
-chained_dict_factory = providers.Factory(
-    providers.Factory(dict, arg1=1),
-    arg1=2,
-)
-print(chained_dict_factory())  # prints: {'arg1': 2}
-
-# 3. Keyword arguments provided from context have most priority
-chained_dict_factory = providers.Factory(
-    providers.Factory(dict, arg1=1),
-    arg1=2,
-)
-print(chained_dict_factory(arg1=3))  # prints: {'arg1': 3}
diff --git a/examples/miniapps/factory_patterns/data.py b/examples/miniapps/factory_patterns/data.py
deleted file mode 100644
index 80fdd20f..00000000
--- a/examples/miniapps/factory_patterns/data.py
+++ /dev/null
@@ -1,41 +0,0 @@
-"""Sample data classes."""
-
-
-class SqlAlchemyDatabaseService:
-    """Database service of an entity."""
-
-    def __init__(self, session, base_class):
-        """Initialize object."""
-        self.session = session
-        self.base_class = base_class
-
-
-class TokensService:
-    """Tokens service."""
-
-    def __init__(self, id_generator, database):
-        """Initialize object."""
-        self.id_generator = id_generator
-        self.database = database
-
-
-class Token:
-    """Token entity."""
-
-
-class UsersService:
-    """Users service."""
-
-    def __init__(self, id_generator, database):
-        """Initialize object."""
-        self.id_generator = id_generator
-        self.database = database
-
-
-class User:
-    """User entity."""
-
-
-# Sample objects
-session = object()
-id_generator = object()
diff --git a/examples/miniapps/factory_patterns/factory_of_factories.py b/examples/miniapps/factory_patterns/factory_of_factories.py
deleted file mode 100644
index 7a6a5fc1..00000000
--- a/examples/miniapps/factory_patterns/factory_of_factories.py
+++ /dev/null
@@ -1,69 +0,0 @@
-"""`Factory of Factories` pattern."""
-
-from dependency_injector import providers
-
-from data import (
-    id_generator,
-    session,
-    SqlAlchemyDatabaseService,
-    TokensService,
-    Token,
-    UsersService,
-    User,
-)
-
-
-# "Factory of Factories" pattern
-
-database_factory = providers.Factory(
-    providers.Factory,
-    SqlAlchemyDatabaseService,
-    session=session,
-)
-
-tokens = providers.Factory(
-    TokensService,
-    id_generator=id_generator,
-    database=database_factory(base_class=Token),
-)
-
-users = providers.Factory(
-    UsersService,
-    id_generator=id_generator,
-    database=database_factory(base_class=User),
-)
-
-tokens_service = tokens()
-assert tokens_service.database.base_class is Token
-
-users_service = users()
-assert users_service.database.base_class is User
-
-# Explanation & some more examples
-
-# 1. Keyword arguments of upper level factory are added to lower level factory
-factory_of_dict_factories = providers.Factory(
-    providers.Factory,
-    dict,
-    arg1=1,
-)
-dict_factory = factory_of_dict_factories(arg2=2)
-print(dict_factory())  # prints: {'arg1': 1, 'arg2': 2}
-
-# 2. Keyword arguments of upper level factory have priority
-factory_of_dict_factories = providers.Factory(
-    providers.Factory,
-    dict,
-    arg1=1,
-)
-dict_factory = factory_of_dict_factories(arg1=2)
-print(dict_factory())  # prints: {'arg1': 2}
-
-# 3. Keyword arguments provided from context have most priority
-factory_of_dict_factories = providers.Factory(
-    providers.Factory,
-    dict,
-    arg1=1,
-)
-dict_factory = factory_of_dict_factories(arg1=2)
-print(dict_factory(arg1=3))  # prints: {'arg1': 3}
diff --git a/examples/miniapps/mail_service/container.py b/examples/miniapps/mail_service/container.py
deleted file mode 100644
index 5603d320..00000000
--- a/examples/miniapps/mail_service/container.py
+++ /dev/null
@@ -1,41 +0,0 @@
-"""Mail service and user registration DI container example."""
-
-from dependency_injector.containers import DeclarativeContainer
-from dependency_injector.providers import Callable, Singleton
-
-import example
-
-
-class Container(DeclarativeContainer):
-    """DI container."""
-
-    mail_service = Singleton(example.MailService,
-                             host='localhost',
-                             port=587,
-                             login='my_login',
-                             password='super_secret_password')
-
-    add_user = Callable(example.add_user,
-                        mailer=mail_service)
-
-
-if __name__ == '__main__':
-    print('Using real mail service:')
-    Container.add_user('sample@mail.com', 'password')
-    # Using real mail service:
-    # Connecting server localhost:587 with my_login:super_secret_password
-    # Sending "Your password is password" to "sample@mail.com"
-
-    print('Using mail service stub:')
-    Container.add_user('sample@mail.com', 'password',
-                       mailer=example.MailServiceStub())
-    # Using mail service stub:
-    # Emulating sending "Your password is password" to "sample@mail.com"
-
-    # Also you can override provider by another provider:
-    Container.mail_service.override(Singleton(example.MailServiceStub))
-    print('Using mail service stub by overriding mail service provider:')
-    Container.add_user('sample@mail.com', 'password')
-    # Using mail service stub by overriding mail service provider:
-    # Emulating sending "Your password is password" to "sample@mail.com"
-    Container.mail_service.reset_override()  # Resetting provider overriding
diff --git a/examples/miniapps/mail_service/example.py b/examples/miniapps/mail_service/example.py
deleted file mode 100644
index 0703e476..00000000
--- a/examples/miniapps/mail_service/example.py
+++ /dev/null
@@ -1,39 +0,0 @@
-"""Mail service and user registration example."""
-
-
-class AbstractMailService:
-    """Abstract mail service."""
-
-    def send(self, email, body):
-        """Send email."""
-        raise NotImplementedError()
-
-
-class MailService(AbstractMailService):
-    """Mail service."""
-
-    def __init__(self, host, port, login, password):
-        """Initialize instance."""
-        self._host = host
-        self._port = port
-        self._login = login
-        self._password = password
-
-    def send(self, email, body):
-        """Send email."""
-        print('Connecting server {0}:{1} with {2}:{3}'.format(
-            self._host, self._port, self._login, self._password))
-        print('Sending "{0}" to "{1}"'.format(body, email))
-
-
-class MailServiceStub(AbstractMailService):
-    """Mail service stub."""
-
-    def send(self, email, body):
-        """Send email."""
-        print('Emulating sending "{0}" to "{1}"'.format(body, email))
-
-
-def add_user(email, password, mailer):
-    """Register user."""
-    mailer.send(email, 'Your password is {0}'.format(password))
diff --git a/examples/miniapps/password-hashing/README.rst b/examples/miniapps/password-hashing/README.rst
new file mode 100644
index 00000000..a979b1e6
--- /dev/null
+++ b/examples/miniapps/password-hashing/README.rst
@@ -0,0 +1,10 @@
+Password hashing
+================
+
+This example demonstrates an injection of the ``Callable`` provider.
+
+Instructions for running:
+
+.. code-block:: bash
+
+    python example.py
diff --git a/examples/miniapps/password-hashing/example.py b/examples/miniapps/password-hashing/example.py
new file mode 100644
index 00000000..e9d042b9
--- /dev/null
+++ b/examples/miniapps/password-hashing/example.py
@@ -0,0 +1,50 @@
+"""Password hashing example."""
+
+from typing import Callable, Dict
+
+import passlib.hash
+
+from dependency_injector import containers, providers
+
+
+class UserService:
+
+    def __init__(self, password_hasher: Callable[[str], str]) -> None:
+        self._password_hasher = password_hasher
+
+    def create_user(self, name: str, password: str) -> Dict[str, str]:
+        hashed_password = self._password_hasher(password)
+        return {
+            'name': name,
+            'password': hashed_password,
+        }
+
+
+class Container(containers.DeclarativeContainer):
+
+    config = providers.Configuration()
+
+    password_hasher = providers.Callable(
+        passlib.hash.sha256_crypt.hash,
+        salt_size=config.salt_size,
+        rounds=config.rounds,
+    )
+
+    user_service = providers.Factory(
+        UserService,
+        password_hasher=password_hasher.provider,
+    )
+
+
+if __name__ == '__main__':
+    container = Container(
+        config={
+            'salt_size': 16,
+            'rounds': 10000,
+        },
+    )
+
+    user_service = container.user_service()
+
+    user = user_service.create_user(name='Roman', password='secret1')
+    print(user)
diff --git a/examples/miniapps/password_hashing/README.rst b/examples/miniapps/password_hashing/README.rst
deleted file mode 100644
index 9c306ab5..00000000
--- a/examples/miniapps/password_hashing/README.rst
+++ /dev/null
@@ -1,12 +0,0 @@
-Dependency injection and password hashing in Python
-===================================================
-
-Small example that demonstrates using of dependency injection for user
-password hashing.
-
-
-instructions for running:
-
-.. code-block:: bash
-
-    python example.py
diff --git a/examples/miniapps/password_hashing/example.py b/examples/miniapps/password_hashing/example.py
deleted file mode 100644
index 1273330e..00000000
--- a/examples/miniapps/password_hashing/example.py
+++ /dev/null
@@ -1,42 +0,0 @@
-"""Example of dependency injection and password hashing in Python."""
-
-import passlib.hash
-
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
-
-
-class UsersService:
-    """Users service."""
-
-    def __init__(self, password_hasher):
-        """Initialize instance."""
-        self._password_hasher = password_hasher
-
-    def create_user(self, name, password):
-        """Create user with hashed password."""
-        hashed_password = self._password_hasher(password)
-        return dict(name=name, password=hashed_password)
-
-
-class Container(containers.DeclarativeContainer):
-    """Inversion of control container."""
-
-    password_hasher = providers.Callable(
-        passlib.hash.sha256_crypt.hash,
-        salt_size=16,
-        rounds=10000)
-
-    users_service = providers.Factory(
-        UsersService,
-        password_hasher=password_hasher.provider)
-
-
-if __name__ == '__main__':
-    container = Container()
-    users_service = container.users_service()
-
-    user1 = users_service.create_user(name='Roman', password='secret1')
-    user2 = users_service.create_user(name='Vitaly', password='secret2')
-
-    print(user1, user2)
diff --git a/examples/miniapps/use-cases/README.rst b/examples/miniapps/use-cases/README.rst
new file mode 100644
index 00000000..c2de398a
--- /dev/null
+++ b/examples/miniapps/use-cases/README.rst
@@ -0,0 +1,11 @@
+Use cases
+=========
+
+This example demonstrates a usage of the ``DependenciesContainer`` provider.
+
+Instructions for running:
+
+.. code-block:: bash
+
+    python -m example prod example@example.com
+    python -m example test example@example.com
diff --git a/examples/miniapps/use-cases/example/__init__.py b/examples/miniapps/use-cases/example/__init__.py
new file mode 100644
index 00000000..1c744ca5
--- /dev/null
+++ b/examples/miniapps/use-cases/example/__init__.py
@@ -0,0 +1 @@
+"""Top-level package."""
diff --git a/examples/miniapps/use_cases/run.py b/examples/miniapps/use-cases/example/__main__.py
similarity index 56%
rename from examples/miniapps/use_cases/run.py
rename to examples/miniapps/use-cases/example/__main__.py
index 873f908a..01d6741c 100644
--- a/examples/miniapps/use_cases/run.py
+++ b/examples/miniapps/use-cases/example/__main__.py
@@ -1,19 +1,23 @@
-"""Run 'Use Cases' example application."""
+"""Main module."""
 
 import sys
 
-from containers import Adapters, TestAdapters, UseCases
+from .containers import UseCases, Adapters, TestAdapters
 
 
-if __name__ == '__main__':
-    environment, email = sys.argv[1:]
-
+def main(environment: str, email: str) -> None:
     if environment == 'prod':
         adapters = Adapters()
     elif environment == 'test':
         adapters = TestAdapters()
+    else:
+        raise RuntimeError('Unknown environment')
 
     use_cases = UseCases(adapters=adapters)
 
     use_case = use_cases.signup()
     use_case.execute(email)
+
+
+if __name__ == '__main__':
+    main(*sys.argv[1:])
diff --git a/examples/miniapps/use-cases/example/adapters.py b/examples/miniapps/use-cases/example/adapters.py
new file mode 100644
index 00000000..c84496a4
--- /dev/null
+++ b/examples/miniapps/use-cases/example/adapters.py
@@ -0,0 +1,22 @@
+"""Adapters module."""
+
+import abc
+
+
+class EmailSender(metaclass=abc.ABCMeta):
+
+    @abc.abstractmethod
+    def send(self, to: str, body: str) -> None:
+        ...
+
+
+class SmtpEmailSender:
+
+    def send(self, to: str, body: str) -> None:
+        print(f'Sending an email to {to} over SMTP, body="{body}"')
+
+
+class EchoEmailSender:
+
+    def send(self, to: str, body: str) -> None:
+        print(f'Fake sending an email to {to}, body="{body}"')
diff --git a/examples/miniapps/use-cases/example/containers.py b/examples/miniapps/use-cases/example/containers.py
new file mode 100644
index 00000000..f164c68f
--- /dev/null
+++ b/examples/miniapps/use-cases/example/containers.py
@@ -0,0 +1,25 @@
+"""Containers module."""
+
+from dependency_injector import containers, providers
+
+from . import adapters, usecases
+
+
+class Adapters(containers.DeclarativeContainer):
+
+    email_sender = providers.Singleton(adapters.SmtpEmailSender)
+
+
+class TestAdapters(containers.DeclarativeContainer):
+
+    email_sender = providers.Singleton(adapters.EchoEmailSender)
+
+
+class UseCases(containers.DeclarativeContainer):
+
+    adapters = providers.DependenciesContainer()
+
+    signup = providers.Factory(
+        usecases.SignupUseCase,
+        email_sender=adapters.email_sender,
+    )
diff --git a/examples/miniapps/use-cases/example/usecases.py b/examples/miniapps/use-cases/example/usecases.py
new file mode 100644
index 00000000..dd03f5c7
--- /dev/null
+++ b/examples/miniapps/use-cases/example/usecases.py
@@ -0,0 +1,22 @@
+"""Use cases module."""
+
+import abc
+
+from .adapters import EmailSender
+
+
+class UseCase(metaclass=abc.ABCMeta):
+
+    @abc.abstractmethod
+    def execute(self) -> None:
+        ...
+
+
+class SignupUseCase:
+
+    def __init__(self, email_sender: EmailSender) -> None:
+        self.email_sender = email_sender
+
+    def execute(self, email: str) -> None:
+        print(f'Sign up user {email}')
+        self.email_sender.send(email, f'Welcome, {email}')
diff --git a/examples/miniapps/use_cases/README.rst b/examples/miniapps/use_cases/README.rst
deleted file mode 100644
index 44db341b..00000000
--- a/examples/miniapps/use_cases/README.rst
+++ /dev/null
@@ -1,9 +0,0 @@
-Dependency Injector Use Cases example
-=====================================
-
-Instructions for running
-
-.. code-block:: bash
-
-    python run.py prod example@example.com  # Running in "production" environment
-    python run.py test example@example.com  # Running in "testing" environment
diff --git a/examples/miniapps/use_cases/containers.py b/examples/miniapps/use_cases/containers.py
deleted file mode 100644
index 847fada3..00000000
--- a/examples/miniapps/use_cases/containers.py
+++ /dev/null
@@ -1,30 +0,0 @@
-"""Dependency injection containers for 'Use Cases' example application."""
-
-from dependency_injector import containers, providers
-
-from example.adapters import SmtpEmailSender, EchoEmailSender
-from example.use_cases import SignupUseCase
-
-
-class Adapters(containers.DeclarativeContainer):
-    """Adapters container."""
-
-    email_sender = providers.Singleton(SmtpEmailSender)
-
-
-class TestAdapters(containers.DeclarativeContainer):
-    """Adapters container.
-
-    This container is used for testing purposes.
-    """
-
-    email_sender = providers.Singleton(EchoEmailSender)
-
-
-class UseCases(containers.DeclarativeContainer):
-    """Use cases container."""
-
-    adapters = providers.DependenciesContainer()
-
-    signup = providers.Factory(SignupUseCase,
-                               email_sender=adapters.email_sender)
diff --git a/examples/miniapps/use_cases/example/__init__.py b/examples/miniapps/use_cases/example/__init__.py
deleted file mode 100644
index bfa99aa2..00000000
--- a/examples/miniapps/use_cases/example/__init__.py
+++ /dev/null
@@ -1 +0,0 @@
-"""Example top-level package."""
diff --git a/examples/miniapps/use_cases/example/adapters.py b/examples/miniapps/use_cases/example/adapters.py
deleted file mode 100644
index d940cf0a..00000000
--- a/examples/miniapps/use_cases/example/adapters.py
+++ /dev/null
@@ -1,25 +0,0 @@
-"""Example adapters package."""
-
-
-class EmailSender:
-    """Abstract email sender."""
-
-    def send(self, to, body):
-        """Send email to specified email."""
-        raise NotImplementedError()
-
-
-class SmtpEmailSender:
-    """SMTP email sender uses SMTP protocol for sending emails."""
-
-    def send(self, to, body):
-        """Send email to specified email."""
-        # Send email via SMTP
-
-
-class EchoEmailSender:
-    """Echo email sender prints emails to stdout."""
-
-    def send(self, to, body):
-        """Send email to specified email."""
-        print('Sending email to "{0}", body = "{1}"'.format(to, body))
diff --git a/examples/miniapps/use_cases/example/use_cases.py b/examples/miniapps/use_cases/example/use_cases.py
deleted file mode 100644
index 4946ae46..00000000
--- a/examples/miniapps/use_cases/example/use_cases.py
+++ /dev/null
@@ -1,22 +0,0 @@
-"""Example use cases package."""
-
-
-class UseCase:
-    """Abstract use case."""
-
-    def execute(self):
-        """Execute use case handling."""
-        raise NotImplementedError()
-
-
-class SignupUseCase:
-    """Sign up use cases registers users."""
-
-    def __init__(self, email_sender):
-        """Initialize instance."""
-        self.email_sender = email_sender
-
-    def execute(self, email):
-        """Execute use case handling."""
-        print('Sign up user {0}'.format(email))
-        self.email_sender.send(email, 'Welcome, "{}"'.format(email))
diff --git a/src/dependency_injector/__init__.py b/src/dependency_injector/__init__.py
index 4e3e13c4..1b7b4e85 100644
--- a/src/dependency_injector/__init__.py
+++ b/src/dependency_injector/__init__.py
@@ -1,6 +1,6 @@
 """Dependency injector top-level package."""
 
-__version__ = '3.40.0'
+__version__ = '3.41.0'
 """Version number that follows semantic versioning.
 
 :type: str
diff --git a/src/dependency_injector/containers.pyi b/src/dependency_injector/containers.pyi
index 62117b43..1c5346bf 100644
--- a/src/dependency_injector/containers.pyi
+++ b/src/dependency_injector/containers.pyi
@@ -24,7 +24,7 @@ class DynamicContainer(Container): ...
 class DeclarativeContainer(Container):
     cls_providers: ClassVar[Dict[str, Provider]]
     inherited_providers: ClassVar[Dict[str, Provider]]
-    def __init__(self, **overriding_providers: Provider) -> None: ...
+    def __init__(self, **overriding_providers: Union[Provider, Any]) -> None: ...
 
 
 def override(container: Container) -> _Callable[[Container], Container]: ...