'Confirm that a given tag is set on the resource.
For more information, please refer to the official API reference:
http://developer.openstack.org/api-ref/networking/v2/index.html#confirm-a-tag'

def check_tag_existence(self, resource_type, resource_id, tag):

    uri = ('%s/%s/%s/tags/%s' % (self.uri_prefix, resource_type, resource_id, tag))
    (resp, _) = self.get(uri)
    self.expected_success(204, resp.status)
    return rest_client.ResponseBody(resp)
