Yog Script (.ys, .yns) analyzed: its lexer, parser and syntax tree, names resolved, the class index model — what the build and the editors read a source with.
namespace System;
/// What an event tells its handlers, beyond who raised it: the base of
/// every event's arguments (`EventArgs.Empty` when there's nothing more).
public class EventArgs {
/// No arguments.
public static readonly EventArgs Empty = new EventArgs();
}