code: def get_asset_form_for_update(self, asset_id=None):
          
          if asset_id is None:
              raise NullArgument()
          try:
              url_path = construct_url('assets',
                                       bank_id=self._catalog_idstr,
                                       asset_id=asset_id)
              asset = objects.Asset(self._get_request(url_path))
          except Exception:
              raise
          asset_form = objects.AssetForm(asset._my_map)
          self._forms[asset_form.get_id().get_identifier()] = not UPDATED
          return asset_form
docs: Gets the asset form for updating an existing asset.
  
          A new asset form should be requested for each update
          transaction.
  
          :param asset_id: the ``Id`` of the ``Asset``
          :type asset_id: ``osid.id.Id``
          :return: the asset form
          :rtype: ``osid.repository.AssetForm``
          :raise: ``NotFound`` -- ``asset_id`` is not found
          :raise: ``NullArgument`` -- ``asset_id`` is null
          :raise: ``OperationFailed`` -- unable to complete request
          :raise: ``PermissionDenied`` -- authorization failure
  
          *compliance: mandatory -- This method must be implemented.*