code: def to_glyphs_family_user_data_from_ufo(self, ufo):
      
      target_user_data = self.font.userData
      try:
          for key, value in ufo.lib[FONT_USER_DATA_KEY].items():
              # Existing values taken from the designspace lib take precedence
              if key not in target_user_data.keys():
                  target_user_data[key] = value
      except KeyError:
          # No FONT_USER_DATA in ufo.lib
          pass
docs: Set the GSFont userData from the UFO family-wide lib data.