added Safe.DispatchEvent() a legacy equivalent for '?.Invoke()' added Safe.Dispose(IEnumerable) added PromiseExtensions.CancellationPoint to add a cancellation point to the chain of promises added IPromise<T> PromiseExtensions.Then<T>(this IPromise<T> that, Action<T> success) overloads added PromiseExtensions.Error() overloads to handle a error or(and) a cancellation

using Implab;

namespace Implab.Automaton.RegularExpressions {
    public class EmptyToken: Token {
        public override void Accept(IVisitor visitor) {
            Safe.ArgumentNotNull(visitor, "visitor");
            visitor.Visit(this);
        }
        public override string ToString() {
            return "$";
        }
    }
}