private void ParseExpression()
        {
            _parser.Expect(SIGNATURE_EXPRESSION);
            _parser.Read(OPEN_EXPRESSION);
            var offset     = _parser.Current.Context;
            var expression = _parser.ReadUntil(TokenType.Seperator, CLOSE_EXPRESSION);

            _parser.Expect(CLOSE_EXPRESSION);
            try
            {
                _templateParsed.Add(new ExpressionPart(_expressionLib.Parse(expression, offset)));
            }
            catch (ExceptionWithContext ewc)
            {
//                ewc.Update(offset.Add(ewc.Context));
                throw ewc;
            }
        }