lib/plugins/aws/customResources/resources/cognitoUserPool/handler.js/handler
function handler(event, context) {
  if (event.RequestType === 'Create') {
    return create(event, context);
  } else if (event.RequestType === 'Update') {
    return update(event, context);
  } else if (event.RequestType === 'Delete') {
    return remove(event, context);
  }
  throw new Error(`Unhandled RequestType ${event.RequestType}`);
}