code: def configure(self, default_settings=global_settings, **options):
          
          if self._wrapped is not empty:
              raise RuntimeError('Settings already configured.')
          holder = UserSettingsHolder(default_settings)
          for name, value in options.items():
              setattr(holder, name, value)
          self._wrapped = holder
docs: Called to manually configure the settings. The 'default_settings'
          parameter sets where to retrieve any unspecified values from (its
          argument must support attribute access (__getattr__)).