def modify_image_attribute(image_id, attribute, operation_type = nil, vars = {})
params = {'ImageId' => image_id,
'Attribute' => attribute}
params['OperationType'] = operation_type if operation_type
params.update(amazonize_list('UserId', vars[:user_id])) if vars[:user_id]
params.update(amazonize_list('UserGroup', vars[:user_group])) if vars[:user_group]
params.update(amazonize_list('ProductCode', vars[:product_code])) if vars[:product_code]
link = generate_request("ModifyImageAttribute", params)
request_info(link, RightBoolResponseParser.new(:logger => @logger))
rescue Exception
on_exception
end