public ParsingException(ParsingSession session, Parser parser, string after = "(not given)", string before = "(not given)")
            : base(string.Format(
				"Expected {0} at line {1}, offset {2}, col {3}, after {4}, before {5}", 
					parser.ToString(), 
					session.CurrentLine.ToString(), 
					session.Offset.ToString(),
					session.CurrentColumn.ToString(),
					after, before))
        {
        }