diff --git a/README.rst b/README.rst
index 61cff790..a7347028 100644
--- a/README.rst
+++ b/README.rst
@@ -52,7 +52,7 @@ What is ``Dependency Injector``?
 
 ``Dependency Injector`` is a dependency injection framework for Python.
 
-It helps you implement the dependency injection principle.
+It helps you in implementing the dependency injection principle.
 
 What is dependency injection?
 -----------------------------
@@ -70,6 +70,9 @@ Before:
 
 .. code-block:: python
 
+   import os
+
+
    class ApiClient:
 
        def __init__(self):
@@ -82,10 +85,18 @@ Before:
        def __init__(self):
            self.api_client = ApiClient()
 
+
+   if __name__ == '__main__':
+       service = Service()
+
+
 After:
 
 .. code-block:: python
 
+   import os
+
+
    class ApiClient:
 
        def __init__(self, api_key: str, timeout: int):
@@ -98,55 +109,82 @@ After:
        def __init__(self, api_client: ApiClient):
            self.api_client = api_client
 
-Who creates the objects now? Look at the next section.
+
+   if __name__ == '__main__':
+       service = Service(ApiClient(os.getenv('API_KEY'), os.getenv('TIMEOUT')))
+
+
+Flexibility comes with a price: now you need to assemble your objects like this
+``Service(ApiClient(os.getenv('API_KEY'), os.getenv('TIMEOUT')))``. The assembly code might get
+duplicated and it'll become harder to change the application structure.
 
 What does Dependency Injector do?
 ---------------------------------
 
-``Dependency Injector`` provides you with the container and the providers that help you build
-your application objects when you apply dependency injection principle:
+``Dependency Injector`` helps you assemble the objects.
+
+It provides you the container and the providers that help you describe objects assembly. When you
+need an object you get it from the container. The rest of the assembly work is done by the
+framework:
 
 .. code-block:: python
 
-    from dependency_injector import containers, providers
+   from dependency_injector import containers, providers
 
 
-    class ApiClient:
+   class ApiClient:
 
-        def __init__(self, api_key: str, timeout: int):
-            self.api_key = api_key
-            self.timeout = timeout
+       def __init__(self, api_key: str, timeout: int):
+           self.api_key = api_key
+           self.timeout = timeout
 
 
-    class Service:
+   class Service:
 
-        def __init__(self, api_client: ApiClient):
-            self.api_client = api_client
+       def __init__(self, api_client: ApiClient):
+           self.api_client = api_client
 
 
-    class Container(containers.DeclarativeContainer):
+   class Container(containers.DeclarativeContainer):
 
-        config = providers.Configuration()
+       config = providers.Configuration()
 
-        api_client = providers.Singleton(
-            ApiClient,
-            api_key=config.api_key,
-            timeout=config.timeout,
-        )
+       api_client = providers.Singleton(
+           ApiClient,
+           api_key=config.api_key,
+           timeout=config.timeout,
+       )
 
-        service = providers.Factory(
-            Service,
-            api_client=api_client,
-        )
+       service = providers.Factory(
+           Service,
+           api_client=api_client,
+       )
 
 
-    if __name__ == '__main__':
-        container = Container()
-        container.config.from_yaml('config.yml')
+   if __name__ == '__main__':
+       container = Container()
+       container.config.api_key.from_env('API_KEY')
+       container.config.timeout.from_env('TIMEOUT')
 
-        service = container.service()
+       service = container.service()
+       assert isinstance(service.api_client, ApiClient)
 
-        assert isinstance(service.api_client, ApiClient)
+Retrieving of the ``Service`` instance now is done like this ``container.service()``.
+
+Also ``Dependency Injector`` provides a bonus in overriding any of the providers with the
+``.override()`` method:
+
+.. code-block:: python
+
+   from unittest import mock
+
+
+   with container.api_client.override(mock.Mock()):
+       service = container.service()
+       assert isinstance(service.api_client, mock.Mock)
+
+It helps in a testing. Also you can use it for configuring project for the different environments:
+replace an API client with a stub on the dev or stage.
 
 `More examples <https://github.com/ets-labs/python-dependency-injector/tree/master/examples>`_
 
diff --git a/docs/containers/declarative.rst b/docs/containers/declarative.rst
index 045e9c6e..5f362b31 100644
--- a/docs/containers/declarative.rst
+++ b/docs/containers/declarative.rst
@@ -1,55 +1,43 @@
-Declarative containers
-----------------------
+Declarative container
+---------------------
 
 .. currentmodule:: dependency_injector.containers
 
-:py:class:`DeclarativeContainer` is inversion of control container that 
-could be defined in declarative manner. It should cover most of the cases 
-when list of providers that would be included in container is deterministic 
-(container will not change its structure in runtime).
+:py:class:`DeclarativeContainer` is a class-based style of the providers definition.
 
-Declarative containers have to extend base declarative container class - 
-:py:class:`dependency_injector.containers.DeclarativeContainer`.
-
-Declarative container's providers have to be defined like container's class 
-attributes. Every provider in container has name. This name should follow 
-``some_provider`` convention, that is standard naming convention for 
-attribute names in Python.
-
-.. note::
-
-    Declarative containers have several features that could be useful 
-    for some kind of operations on container's providers, please visit API 
-    documentation for getting full list of features - 
-    :py:class:`dependency_injector.containers.DeclarativeContainer`.
-
-Here is an simple example of defining declarative container with several 
-factories:
-
-.. image:: /images/containers/declarative.png
-    :width: 85%
-    :align: center
+You create the declarative container subclass, put the providers as attributes and create the
+container instance.
 
 .. literalinclude:: ../../examples/containers/declarative.py
    :language: python
+   :lines: 3-
 
-Example of declarative containers inheritance:
+The declarative container providers should only be used when you have the container instance.
+Working with the providers of the container on the class level will influence all further
+instances.
 
-.. image:: /images/containers/declarative_inheritance.png
-    :width: 100%
-    :align: center
+The declarative container can not have any methods or any other attributes then providers.
+
+The container class provides next attributes:
+
+- ``providers`` - the dictionary of all the container providers
+- ``cls_providers`` - the dictionary of the container providers of the current container
+- ``inherited_providers`` - the dictionary of all the inherited container providers
 
 .. literalinclude:: ../../examples/containers/declarative_inheritance.py
    :language: python
+   :lines: 3-
 
-Example of declarative containers's provider injections:
-
-.. image:: /images/containers/declarative_injections.png
-    :width: 100%
-    :align: center
+Injections in the declarative container are done the usual way:
 
 .. literalinclude:: ../../examples/containers/declarative_injections.py
    :language: python
+   :lines: 3-
 
+You can override the container providers when you create the container instance:
+
+.. literalinclude:: ../../examples/containers/declarative_override_providers.py
+   :language: python
+   :lines: 3-
 
 .. disqus::
diff --git a/docs/containers/dynamic.rst b/docs/containers/dynamic.rst
index bd879f23..856ad7c4 100644
--- a/docs/containers/dynamic.rst
+++ b/docs/containers/dynamic.rst
@@ -1,28 +1,25 @@
-Dynamic containers
-------------------
+Dynamic container
+-----------------
 
 .. currentmodule:: dependency_injector.containers
 
-:py:class:`DynamicContainer` is an inversion of control container with dynamic 
-structure. It should cover most of the cases when list of providers that 
-would be included in container is non-deterministic and depends on 
-application's flow or its configuration (container's structure could be 
-determined just after application will be started and will do some initial 
-work, like parsing list of container's providers from the configuration).
+:py:class:`DynamicContainer` is a collection of the providers defined in the runtime.
 
-While :py:class:`DeclarativeContainer` acts on class-level, 
-:py:class:`DynamicContainer` does the same on instance-level.
-
-Here is an simple example of defining dynamic container with several factories:
+You create the dynamic container instance and put the providers as attributes.
 
 .. literalinclude:: ../../examples/containers/dynamic.py
    :language: python
+   :lines: 3-
 
-Next example demonstrates creation of dynamic container based on some 
-configuration:
+The dynamic container is good for the case when your application structure depends on the
+configuration file or some other source that you can reach only after application is already
+running (database, api, etc).
+
+In this example we use the configuration to fill in the dynamic container with the providers:
 
 .. literalinclude:: ../../examples/containers/dynamic_runtime_creation.py
    :language: python
-
+   :lines: 3-
 
 .. disqus::
+
diff --git a/docs/containers/index.rst b/docs/containers/index.rst
index 93bee78a..510d4d02 100644
--- a/docs/containers/index.rst
+++ b/docs/containers/index.rst
@@ -1,21 +1,16 @@
-IoC Containers
-==============
+Containers
+==========
 
-Containers are collections of providers. Main purpose of containers is to group
-providers. 
+Containers are collections of the providers.
 
-There are, actually, several popular cases of containers usage:
+There are several use cases how you can use containers:
 
-+ Keeping all providers in a single container.
-+ Grouping of providers from the same architectural layer (for example, 
++ Keeping all the providers in a single container (most common).
++ Grouping of the providers from the same architectural layer (for example,
   ``Services``, ``Models`` and ``Forms`` containers).
 + Grouping of providers from the same functional groups (for example,
-  container ``Users``, that contains all functional parts of ``Users``
-  component).
-
-Also, for both of these and some other cases, it might be useful to attach 
-some init / shutdown functionality or something else, that deals with group 
-of providers.
+  container ``Users``, that contains all functional parts of the ``users``
+  package).
 
 Containers package API docs - :py:mod:`dependency_injector.containers`.
 
diff --git a/docs/containers/overriding.rst b/docs/containers/overriding.rst
index 729a8b1c..cf5627af 100644
--- a/docs/containers/overriding.rst
+++ b/docs/containers/overriding.rst
@@ -1,41 +1,24 @@
-Overriding of containers
-------------------------
+Overriding of the container
+---------------------------
 
 .. currentmodule:: dependency_injector.containers
 
-Containers can be overridden by other containers. This, actually, means that 
-all of the providers from overriding container will override providers with 
-the same names in overridden container.
+The container can be overridden by the other container. All of the providers from the overriding
+container will override the providers with the same names in the overridden container.
 
-There are two ways to override :py:class:`DeclarativeContainer` with another 
-container:
-
-- Use :py:meth:`DeclarativeContainer.override` method.
-- Use :py:func:`override` class decorator.
-
-Example of overriding container using :py:meth:`DeclarativeContainer.override` 
-method:
-
-.. literalinclude:: ../../examples/containers/override_declarative.py
+.. literalinclude:: ../../examples/containers/override.py
    :language: python
+   :lines: 3-
 
-Example of overriding container using :py:func:`override` decorator:
+It helps in a testing. Also you can use it for configuring project for the different
+environments: replace an API client with a stub on the dev or stage.
 
-.. literalinclude:: ../../examples/containers/override_declarative_decorator.py
-   :language: python
+The container also has:
 
-Also there are several useful :py:class:`DeclarativeContainer` methods and 
-properties that help to work with container overridings:
-
-- :py:attr:`DeclarativeContainer.overridden` - tuple of all overriding 
-  containers.
-- :py:meth:`DeclarativeContainer.reset_last_overriding()` - reset last 
-  overriding provider for each container providers.
-- :py:meth:`DeclarativeContainer.reset_override()` - reset all overridings 
-  for each container providers. 
-
-:py:class:`DynamicContainer` has exactly the same functionality, except of 
-:py:func:`override` decorator.
+- ``container.overridden`` - tuple of all overriding containers.
+- ``container.reset_last_overriding()`` - reset last overriding for each provider in the container.
+- ``container.reset_override()`` - reset all overriding in the container.
 
+:py:class:`DynamicContainer` has the same functionality.
 
 .. disqus::
diff --git a/docs/containers/specialization.rst b/docs/containers/specialization.rst
index 1c2619f1..724d0bd1 100644
--- a/docs/containers/specialization.rst
+++ b/docs/containers/specialization.rst
@@ -1,25 +1,25 @@
-Specialization of containers
-----------------------------
+Specialization of the container provider type
+---------------------------------------------
 
 .. currentmodule:: dependency_injector.containers
 
-:py:class:`DeclarativeContainer` could be specialized for any kind of needs 
-via declaring its subclasses. 
-
-One of such `builtin` features is a limitation for providers type.
-
-Next example shows usage of this feature with :py:class:`DeclarativeContainer` 
-in couple with feature of :py:class:`dependency_injector.providers.Factory` 
-for limitation of its provided type:
+You can make a restriction of the :py:class:`DeclarativeContainer` provider type:
 
 .. literalinclude:: ../../examples/containers/declarative_provider_type.py
    :language: python
+   :lines: 3-
+   :emphasize-lines: 29-31
 
-Limitation for providers type could be used with :py:class:`DynamicContainer` 
-as well:
+The emphasized lines will cause an error because ``other_provider`` is not a subtype of the
+``ServiceProvider``. This helps to control the content of the container.
+
+The same works for the :py:class:`DynamicContainer`:
 
 .. literalinclude:: ../../examples/containers/dynamic_provider_type.py
    :language: python
+   :lines: 3-
+   :emphasize-lines: 23
 
+The emphasized line will also cause an error.
 
 .. disqus::
diff --git a/docs/images/containers/declarative.png b/docs/images/containers/declarative.png
deleted file mode 100644
index 11b0297d..00000000
Binary files a/docs/images/containers/declarative.png and /dev/null differ
diff --git a/docs/images/containers/declarative_inheritance.png b/docs/images/containers/declarative_inheritance.png
deleted file mode 100644
index 1e0eb1f4..00000000
Binary files a/docs/images/containers/declarative_inheritance.png and /dev/null differ
diff --git a/docs/images/containers/declarative_injections.png b/docs/images/containers/declarative_injections.png
deleted file mode 100644
index 36454e5b..00000000
Binary files a/docs/images/containers/declarative_injections.png and /dev/null differ
diff --git a/docs/main/changelog.rst b/docs/main/changelog.rst
index 403e11a0..1061b171 100644
--- a/docs/main/changelog.rst
+++ b/docs/main/changelog.rst
@@ -7,6 +7,11 @@ that were made in every particular version.
 From version 0.7.6 *Dependency Injector* framework strictly 
 follows `Semantic versioning`_
 
+3.30.3
+------
+- Update README.
+- Update containers documentation and examples.
+
 3.30.2
 ------
 - Update README.
diff --git a/examples/containers/declarative.py b/examples/containers/declarative.py
index f095d5e9..4fb7d795 100644
--- a/examples/containers/declarative.py
+++ b/examples/containers/declarative.py
@@ -1,23 +1,23 @@
-"""Declarative IoC container simple example."""
+"""Declarative container example."""
 
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
+from dependency_injector import containers, providers
 
 
-# Defining declarative IoC container:
 class Container(containers.DeclarativeContainer):
-    """Example IoC container."""
 
     factory1 = providers.Factory(object)
 
     factory2 = providers.Factory(object)
 
 
-# Creating some objects:
-object1 = Container.factory1()
-object2 = Container.factory2()
+if __name__ == '__main__':
+    container = Container()
 
-# Making some asserts:
-assert object1 is not object2
-assert isinstance(object1, object)
-assert isinstance(object2, object)
+    object1 = container.factory1()
+    object2 = container.factory2()
+
+    print(container.providers)
+    # {
+    #     'factory1': <dependency_injector.providers.Factory(...),
+    #     'factory2': <dependency_injector.providers.Factory(...),
+    # }
diff --git a/examples/containers/declarative_inheritance.py b/examples/containers/declarative_inheritance.py
index ed2fa531..14621dad 100644
--- a/examples/containers/declarative_inheritance.py
+++ b/examples/containers/declarative_inheritance.py
@@ -1,30 +1,34 @@
-"""Declarative IoC containers inheritance example."""
+"""Declarative containers inheritance example."""
 
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
+from dependency_injector import containers, providers
 
 
 class ContainerA(containers.DeclarativeContainer):
-    """Example IoC container A."""
 
     provider1 = providers.Factory(object)
 
 
 class ContainerB(ContainerA):
-    """Example IoC container B."""
 
     provider2 = providers.Singleton(object)
 
 
-# Making some asserts for `providers` attribute:
-assert ContainerA.providers == dict(provider1=ContainerA.provider1)
-assert ContainerB.providers == dict(provider1=ContainerA.provider1,
-                                    provider2=ContainerB.provider2)
+assert ContainerA.providers == {
+    'provider1': ContainerA.provider1,
+}
+assert ContainerB.providers == {
+    'provider1': ContainerA.provider1,
+    'provider2': ContainerB.provider2,
+}
 
-# Making some asserts for `cls_providers` attribute:
-assert ContainerA.cls_providers == dict(provider1=ContainerA.provider1)
-assert ContainerB.cls_providers == dict(provider2=ContainerB.provider2)
+assert ContainerA.cls_providers == {
+    'provider1': ContainerA.provider1,
+}
+assert ContainerB.cls_providers == {
+    'provider2': ContainerB.provider2,
+}
 
-# Making some asserts for `inherited_providers` attribute:
-assert ContainerA.inherited_providers == dict()
-assert ContainerB.inherited_providers == dict(provider1=ContainerB.provider1)
+assert ContainerA.inherited_providers == {}
+assert ContainerB.inherited_providers == {
+    'provider1': ContainerA.provider1,
+}
diff --git a/examples/containers/declarative_injections.py b/examples/containers/declarative_injections.py
index 2a9fbdc5..abfe9505 100644
--- a/examples/containers/declarative_injections.py
+++ b/examples/containers/declarative_injections.py
@@ -1,35 +1,42 @@
-"""Declarative IoC container's provider injections example."""
+"""Declarative container injections example."""
 
 import sqlite3
-import collections
 
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
+from dependency_injector import containers, providers
 
 
-UsersService = collections.namedtuple('UsersService', ['db'])
-AuthService = collections.namedtuple('AuthService', ['db', 'users_service'])
+class UserService:
+    def __init__(self, db: sqlite3.Connection):
+        self.db = db
 
 
-class Services(containers.DeclarativeContainer):
-    """IoC container of service providers."""
+class AuthService:
+    def __init__(self, db: sqlite3.Connection, user_service: UserService):
+        self.db = db
+        self.user_service = user_service
+
+
+class Container(containers.DeclarativeContainer):
 
     database = providers.Singleton(sqlite3.connect, ':memory:')
 
-    users = providers.Factory(UsersService,
-                              db=database)
+    user_service = providers.Factory(
+        UserService,
+        db=database,
+    )
 
-    auth = providers.Factory(AuthService,
-                             db=database,
-                             users_service=users)
+    auth_service = providers.Factory(
+        AuthService,
+        db=database,
+        user_service=user_service,
+    )
 
 
-# Retrieving service providers from container:
-users_service = Services.users()
-auth_service = Services.auth()
+if __name__ == '__main__':
+    container = Container()
 
-# Making some asserts:
-assert users_service.db is auth_service.db is Services.database()
-assert isinstance(auth_service.users_service, UsersService)
-assert users_service is not Services.users()
-assert auth_service is not Services.auth()
+    user_service = container.user_service()
+    auth_service = container.auth_service()
+
+    assert user_service.db is auth_service.db is container.database()
+    assert isinstance(auth_service.user_service, UserService)
diff --git a/examples/containers/declarative_override_providers.py b/examples/containers/declarative_override_providers.py
new file mode 100644
index 00000000..0e92c1df
--- /dev/null
+++ b/examples/containers/declarative_override_providers.py
@@ -0,0 +1,18 @@
+"""Declarative container provider override example."""
+
+import sqlite3
+from unittest import mock
+
+from dependency_injector import containers, providers
+
+
+class Container(containers.DeclarativeContainer):
+
+    database = providers.Singleton(sqlite3.connect, ':memory:')
+
+
+if __name__ == '__main__':
+    container = Container(database=mock.Mock(sqlite3.Connection))
+
+    database = container.database()
+    assert isinstance(database, mock.Mock)
diff --git a/examples/containers/declarative_provider_type.py b/examples/containers/declarative_provider_type.py
index 2a755726..a52a2c43 100644
--- a/examples/containers/declarative_provider_type.py
+++ b/examples/containers/declarative_provider_type.py
@@ -1,48 +1,33 @@
-"""Specializing declarative container and factory provider example."""
+"""Declarative container provider type restriction example."""
 
-import collections
+import abc
 
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
-import dependency_injector.errors as errors
+from dependency_injector import containers, providers
 
 
-class SequenceProvider(providers.Factory):
-    """Sequence factory.
-
-    Can provide only sequence objects.
-    """
-
-    provided_type = collections.Sequence
+class Service(metaclass=abc.ABCMeta):
+    ...
 
 
-class SequencesContainer(containers.DeclarativeContainer):
-    """IoC container.
-
-    Can contain only sequence providers.
-    """
-
-    provider_type = SequenceProvider
+class UserService(Service):
+    ...
 
 
-if __name__ == '__main__':
-    try:
-        class _SequenceContainer1(SequencesContainer):
-            object_provider = providers.Factory(object)
-    except errors.Error as exception:
-        print(exception)
-        # <class '__main__._SequenceContainer1'> can contain only
-        # <class '__main__.SequenceProvider'> instances
+class ServiceProvider(providers.Factory):
 
-    try:
-        class _SequenceContainer2(SequencesContainer):
-            object_provider = SequenceProvider(object)
-    except errors.Error as exception:
-        print(exception)
-        # <class '__main__.SequenceProvider'> can provide only
-        # <class '_abcoll.Sequence'> instances
+    provided_type = Service
 
-    class _SequenceContaier3(SequencesContainer):
-        list_provider = SequenceProvider(list)
 
-    assert _SequenceContaier3.list_provider() == list()
+class ServiceContainer(containers.DeclarativeContainer):
+
+    provider_type = ServiceProvider
+
+
+class MyServices(ServiceContainer):
+
+    user_service = ServiceProvider(UserService)
+
+
+class ImproperServices(ServiceContainer):
+
+    other_provider = providers.Factory(object)
diff --git a/examples/containers/dynamic.py b/examples/containers/dynamic.py
index cf33dc58..678351d6 100644
--- a/examples/containers/dynamic.py
+++ b/examples/containers/dynamic.py
@@ -1,18 +1,18 @@
-"""Dynamic container simple example."""
+"""Dynamic container example."""
 
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
+from dependency_injector import containers, providers
 
 
-# Defining dynamic container:
-container = containers.DynamicContainer()
-container.factory1 = providers.Factory(object)
-container.factory2 = providers.Factory(object)
+if __name__ == '__main__':
+    container = containers.DynamicContainer()
+    container.factory1 = providers.Factory(object)
+    container.factory2 = providers.Factory(object)
 
-# Creating some objects:
-object1 = container.factory1()
-object2 = container.factory2()
+    object1 = container.factory1()
+    object2 = container.factory2()
 
-# Making some asserts:
-assert object1 is not object2
-assert isinstance(object1, object) and isinstance(object2, object)
+    print(container.providers)
+    # {
+    #     'factory1': <dependency_injector.providers.Factory(...),
+    #     'factory2': <dependency_injector.providers.Factory(...),
+    # }
diff --git a/examples/containers/dynamic_provider_type.py b/examples/containers/dynamic_provider_type.py
index fd1c0ac9..adbb6043 100644
--- a/examples/containers/dynamic_provider_type.py
+++ b/examples/containers/dynamic_provider_type.py
@@ -1,41 +1,25 @@
-"""Specializing dynamic container and factory provider example."""
+"""Dynamic container provider type restriction example."""
 
-import collections
+import abc
 
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
-import dependency_injector.errors as errors
+from dependency_injector import containers, providers
 
 
-class SequenceProvider(providers.Factory):
-    """Sequence factory.
-
-    Can provide only sequence objects.
-    """
-
-    provided_type = collections.Sequence
+class Service(metaclass=abc.ABCMeta):
+    ...
 
 
-sequences_container = containers.DynamicContainer()
-sequences_container.provider_type = SequenceProvider
+class UserService(Service):
+    ...
 
 
-if __name__ == '__main__':
-    try:
-        sequences_container.object_provider = providers.Factory(object)
-    except errors.Error as exception:
-        print(exception)
-        # <dependency_injector.containers.DynamicContainer object at
-        # 0x107820ed0> can contain only <class '__main__.SequenceProvider'>
-        # instances
+class ServiceProvider(providers.Factory):
 
-    try:
-        sequences_container.object_provider = SequenceProvider(object)
-    except errors.Error as exception:
-        print(exception)
-        # <class '__main__.SequenceProvider'> can provide only
-        # <class '_abcoll.Sequence'> instances
+    provided_type = Service
 
-    sequences_container.list_provider = SequenceProvider(list)
 
-    assert sequences_container.list_provider() == list()
+services = containers.DynamicContainer()
+services.provider_type = ServiceProvider
+
+services.user_service = ServiceProvider(UserService)
+services.other_provider = providers.Factory(object)
diff --git a/examples/containers/dynamic_runtime_creation.py b/examples/containers/dynamic_runtime_creation.py
index 2a82cb03..f95114fa 100644
--- a/examples/containers/dynamic_runtime_creation.py
+++ b/examples/containers/dynamic_runtime_creation.py
@@ -1,59 +1,40 @@
-"""Creation of dynamic container based on some configuration example."""
+"""Creation of dynamic container based on the configuration example."""
 
-import collections
-
-import dependency_injector.containers as containers
+from dependency_injector import containers, providers
 
 
-# Defining several example services:
-UsersService = collections.namedtuple('UsersService', [])
-AuthService = collections.namedtuple('AuthService', [])
+class UserService:
+    ...
 
 
-def import_cls(cls_name):
-    """Import class by its fully qualified name.
-
-    In terms of current example it is just a small helper function. Please,
-    don't use it in production approaches.
-    """
-    path_components = cls_name.split('.')
-    module = __import__('.'.join(path_components[:-1]),
-                        locals(),
-                        globals(),
-                        fromlist=path_components[-1:])
-    return getattr(module, path_components[-1])
+class AuthService:
+    ...
 
 
-# "Parsing" some configuration:
-config = {
-    'services': {
-        'users': {
-            'class': '__main__.UsersService',
-            'provider_class': 'dependency_injector.providers.Factory',
+def populate_container(container, providers_config):
+    for provider_name, provider_info in providers_config.items():
+        provided_cls = globals().get(provider_info['class'])
+        provider_cls = getattr(providers, provider_info['provider_class'])
+        setattr(container, provider_name, provider_cls(provided_cls))
+
+
+if __name__ == '__main__':
+    services_config = {
+        'user': {
+            'class': 'UserService',
+            'provider_class': 'Factory',
         },
         'auth': {
-            'class': '__main__.AuthService',
-            'provider_class': 'dependency_injector.providers.Factory',
-        }
+            'class': 'AuthService',
+            'provider_class': 'Factory',
+        },
     }
-}
+    services = containers.DynamicContainer()
 
-# Creating empty container of service providers:
-services = containers.DynamicContainer()
+    populate_container(services, services_config)
 
-# Filling dynamic container with service providers using configuration:
-for service_name, service_info in config['services'].iteritems():
-    # Runtime importing of service and service provider classes:
-    service_cls = import_cls(service_info['class'])
-    service_provider_cls = import_cls(service_info['provider_class'])
+    user_service = services.user()
+    auth_service = services.auth()
 
-    # Binding service provider to the dynamic service providers catalog:
-    setattr(services, service_name, service_provider_cls(service_cls))
-
-# Creating some objects:
-users_service = services.users()
-auth_service = services.auth()
-
-# Making some asserts:
-assert isinstance(users_service, UsersService)
-assert isinstance(auth_service, AuthService)
+    assert isinstance(user_service, UserService)
+    assert isinstance(auth_service, AuthService)
diff --git a/examples/containers/override.py b/examples/containers/override.py
new file mode 100644
index 00000000..268cc4d0
--- /dev/null
+++ b/examples/containers/override.py
@@ -0,0 +1,31 @@
+"""Container overriding example."""
+
+from dependency_injector import containers, providers
+
+
+class Service:
+    ...
+
+
+class ServiceStub:
+    ...
+
+
+class Container(containers.DeclarativeContainer):
+
+    service = providers.Factory(Service)
+
+
+class OverridingContainer(containers.DeclarativeContainer):
+
+    service = providers.Factory(ServiceStub)
+
+
+if __name__ == '__main__':
+    container = Container()
+    overriding_container = OverridingContainer()
+
+    container.override(overriding_container)
+
+    service = container.service()
+    assert isinstance(service, ServiceStub)
diff --git a/examples/containers/override_declarative.py b/examples/containers/override_declarative.py
deleted file mode 100644
index b11d1b2e..00000000
--- a/examples/containers/override_declarative.py
+++ /dev/null
@@ -1,28 +0,0 @@
-"""Declarative IoC container overriding example."""
-
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
-
-
-class Container(containers.DeclarativeContainer):
-    """IoC container."""
-
-    sequence_factory = providers.Factory(list)
-
-
-class OverridingContainer(containers.DeclarativeContainer):
-    """Overriding IoC container."""
-
-    sequence_factory = providers.Factory(tuple)
-
-
-# Overriding `Container` with `OverridingContainer`:
-Container.override(OverridingContainer)
-
-# Creating some objects using overridden container:
-sequence_1 = Container.sequence_factory([1, 2, 3])
-sequence_2 = Container.sequence_factory([3, 2, 1])
-
-# Making some asserts:
-assert Container.overridden == (OverridingContainer,)
-assert sequence_1 == (1, 2, 3) and sequence_2 == (3, 2, 1)
diff --git a/examples/containers/override_declarative_decorator.py b/examples/containers/override_declarative_decorator.py
deleted file mode 100644
index 74165383..00000000
--- a/examples/containers/override_declarative_decorator.py
+++ /dev/null
@@ -1,27 +0,0 @@
-"""Declarative IoC container overriding using `@override()` decorator."""
-
-import dependency_injector.containers as containers
-import dependency_injector.providers as providers
-
-
-class Container(containers.DeclarativeContainer):
-    """IoC container."""
-
-    sequence_factory = providers.Factory(list)
-
-
-# Overriding `Container` with `OverridingContainer`:
-@containers.override(Container)
-class OverridingContainer(containers.DeclarativeContainer):
-    """Overriding IoC container."""
-
-    sequence_factory = providers.Factory(tuple)
-
-
-# Creating some objects using overridden container:
-sequence_1 = Container.sequence_factory([1, 2, 3])
-sequence_2 = Container.sequence_factory([3, 2, 1])
-
-# Making some asserts:
-assert Container.overridden == (OverridingContainer,)
-assert sequence_1 == (1, 2, 3) and sequence_2 == (3, 2, 1)
diff --git a/examples/di_demo2/config.yml b/examples/di_demo2/config.yml
deleted file mode 100644
index b6f36405..00000000
--- a/examples/di_demo2/config.yml
+++ /dev/null
@@ -1,2 +0,0 @@
-api_key: test-key
-timeout: 5
\ No newline at end of file
diff --git a/examples/di_demo2/demo.py b/examples/di_demo2/demo.py
index ccfccd97..02d49f09 100644
--- a/examples/di_demo2/demo.py
+++ b/examples/di_demo2/demo.py
@@ -32,8 +32,8 @@ class Container(containers.DeclarativeContainer):
 
 if __name__ == '__main__':
     container = Container()
-    container.config.from_yaml('config.yml')
+    container.config.api_key.from_env('API_KEY')
+    container.config.timeout.from_env('TIMEOUT')
 
     service = container.service()
-
     assert isinstance(service.api_client, ApiClient)
diff --git a/examples/di_demo2/example_di.py b/examples/di_demo2/example_di.py
new file mode 100644
index 00000000..db85c237
--- /dev/null
+++ b/examples/di_demo2/example_di.py
@@ -0,0 +1,18 @@
+import os
+
+
+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
+
+
+if __name__ == '__main__':
+    service = Service(ApiClient(os.getenv('API_KEY'), os.getenv('TIMEOUT')))
diff --git a/examples/di_demo2/example_no_di.py b/examples/di_demo2/example_no_di.py
new file mode 100644
index 00000000..c567ebd6
--- /dev/null
+++ b/examples/di_demo2/example_no_di.py
@@ -0,0 +1,18 @@
+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()
+
+
+if __name__ == '__main__':
+    service = Service()
diff --git a/examples/di_demo2/test.py b/examples/di_demo2/test.py
new file mode 100644
index 00000000..56310989
--- /dev/null
+++ b/examples/di_demo2/test.py
@@ -0,0 +1,11 @@
+from unittest import mock
+
+from demo import Container
+
+
+if __name__ == '__main__':
+    container = Container()
+
+    with container.api_client.override(mock.Mock()):
+        service = container.service()
+        assert isinstance(service.api_client, mock.Mock)
diff --git a/src/dependency_injector/__init__.py b/src/dependency_injector/__init__.py
index 849437b1..fa0c9dcd 100644
--- a/src/dependency_injector/__init__.py
+++ b/src/dependency_injector/__init__.py
@@ -1,6 +1,6 @@
 """Dependency injector top-level package."""
 
-__version__ = '3.30.2'
+__version__ = '3.30.3'
 """Version number that follows semantic versioning.
 
 :type: str