code: def _save_reference(self, filename):
          
          ## Save the SFrame
          url = _make_internal_url(filename)
  
          with cython_context():
              self.__proxy__.save_reference(url)
docs: Performs an incomplete save of an existing SFrame into a directory.
          This saved SFrame may reference SFrames in other locations in the same
          filesystem for certain resources.
  
          Parameters
          ----------
          filename : string
              The location to save the SFrame. Either a local directory or a
              remote URL.
  
          See Also
          --------
          load_sframe, SFrame
  
          Examples
          --------
          >>> # Save the sframe into binary format
          >>> sf.save_reference('data/training_data_sframe')