code: def set_asset(self, asset_id, asset_content_type=None):
          
          if asset_id is None:
              raise NullArgument('asset_id cannot be None')
          if not isinstance(asset_id, Id):
              raise InvalidArgument('asset_id must be an instance of Id')
          if asset_content_type is not None and not isinstance(asset_content_type, Type):
              raise InvalidArgument('asset_content_type must be instance of Type')
          if asset_content_type is None:
              asset_content_type = ''
          self.my_osid_object_form._my_map['fileId'] = {
              'assetId': str(asset_id),
              'assetContentTypeId': str(asset_content_type)
          }
docs: stub