text: Title: Improve Providers extending
  Body: At the moment, every extended provider have to implement override logic:
  
  ``` python
  class Extended(Provider):
  
      def __call__(self, *args, **kwargs):
          """Return provided instance."""
          if self.overridden:
              return self.last_overriding(*args, **kwargs)
  ```
  
  Need to improve provider extending process.
  