api.any(async () => {
   // or event handler or workflow
   await cancelActivity(activityToken, reason);
   await failActivity(activityToken, error, message);
   await completeActivity(activityToken, result);
})

const myAct = activity(...);
workflow(() => {
   // start activity
   const actInstance = myAct();
   
   // cancel, error, or complete the workflow
   await actInstance.cancel(reason);
   await actInstance.fail(new Error()); // or actInstance.fail(error, message);
   await actInstance.complete(result);

  await actInstance; 
});