docs: def module_config(self, settings_module):
          """
          Optional function
          """
          assert hasattr(settings_module, '__file__'), 'settings must be a module'
          # set root_path according to module file
          self.set_root_path(settings_module=settings_module)
          app_log.debug('Set root_path: %s', self.root_path)
  
          global settings
  
          self.update_settings(dict(
              [(i, getattr(settings_module, i)) for i in dir(settings_module)
               if not i.startswith('_') and i == i.upper()]))
  
          settings._module = settings_module
  
          # keep a mapping to app on settings object
          settings._app = self