def METHOD_NAME(self, request):
    if not request.xpath('//m:StreamingSubscriptionRequest', namespaces=NAMESPACES):  # pragma: no cover
        return
    emails = request.xpath('//t:EmailAddress', namespaces=NAMESPACES)
    assert len(emails) == 1
    assert emails[0].text == self.resource.principal_email
    subscription_id = get_random_string(10)
    self.subscription_to_resource[subscription_id] = self.resource
    return M.SubscribeResponse(
        M.ResponseMessages(
            M.SubscribeResponseMessage(
                M.ResponseCode('NoError'),
                M.SubscriptionId(subscription_id),
                ResponseClass='Success',
            ),
        ),
    )