code: def init_app(self, app):
          
          if not hasattr(app, 'extensions'):  # pragma: no cover
              app.extensions = {}
          app.extensions['imagine'] = self
  
          self._set_defaults(app)
  
          self._redirect_code = app.config['IMAGINE_CACHE_REDIRECT_CODE']
  
          if isinstance(app.config['IMAGINE_ADAPTERS'], dict):
              self._adapters.update(app.config['IMAGINE_ADAPTERS'])
          if isinstance(app.config['IMAGINE_FILTERS'], dict):
              self._filters.update(app.config['IMAGINE_FILTERS'])
  
          self._handle_adapter(app)
          self._handle_filter_sets(app)
  
          self._add_url_rule(app)
docs: :param app: Flask application