scriptlab for outlook - error with function getattachmentsasync

Question

I am a newbie to 'script lab' for outlook. I need to access attachments (open & save, but this question is not that far). I use function "getattachmentsasync", code below, but it raised an error:

["Uncaught TypeError: Office.context.mailbox.item.getAttachmentsAsync is not a function", "https://script-lab-runner.azureedge.net/", 14, 33, TypeError]

code:

$("#run").click(run);
function run() {
  Office.context.mailbox.item.getAttachmentsAsync(function (att) {
    console.log(att)
  } );
}