Add complex provided instance example

examples/providers/provided_instance.py

@@ -34,5 +34,4 @@ client_factory = providers.Factory(
 
 if __name__ == '__main__':
     client = client_factory()
-
     assert client.value1 == client.value2 == client.value3 == 'foo'

examples/providers/provided_instance_complex.py

@@ -0,0 +1,41 @@
+"""Complex example of the injecting of provided instance attributes and items."""
+
+from dependency_injector import providers
+
+
+class Service:
+
+    def __init__(self, value):
+        self.value = value
+
+    def get_value(self):
+        return self.value
+
+
+service = providers.Singleton(Service, value=42)
+
+dependency = providers.Object(
+    {
+        'foo': {
+            'bar': 10,
+            'baz': lambda arg: {'arg': arg}
+        },
+    },
+)
+
+demo_list = providers.List(
+    dependency.provided['foo']['bar'],
+    dependency.provided['foo']['baz'].call(22)['arg'],
+    dependency.provided['foo']['baz'].call(service)['arg'],
+    dependency.provided['foo']['baz'].call(service)['arg'].value,
+    dependency.provided['foo']['baz'].call(service)['arg'].get_value.call(),
+)
+
+if __name__ == '__main__':
+    assert demo_list() == [
+        10,
+        22,
+        service(),
+        42,
+        42,
+    ]