private XmlElementStack start(string name, string xsd = AssertionXsd, string prefix = AssertionPrefix)
        {
            var stack = new XmlElementStack(_document, xsd, prefix);

            stack.Push(name);

            return(stack);
        }
        private void writeAssertion()
        {
            _assertion = start(AssertionElem)
                         .Attr(ID, AssertionIdPrefix + _response.Id)
                         .Attr(IssueInstant, _response.IssueInstant);

            _assertion.Push(Issuer).InnerText = _response.Issuer.ToString();

            _assertion.Pop();
        }