anchor.diff:  
     Options(this._run);
   
  -  bool add(String text, {String named}) {
  -    return _addOption(new Option(text, named: named));
  +  bool add(String text, {String named, Duration delay: Duration.ZERO}) {
  +    return _addOption(new Option(text, named: named), delay: delay);
     }
   
     /// Adds all of the options, and binds them together such that the use of any
  
positive.code: 
    Stream<UseOptionEvent> get uses => _run.every((e) => e is UseOptionEvent);
  
    bool _addOption(Option option) {
      if (!_opts.containsKey(option.name)) {
        _opts[option.name] = option;
        _run.emit(new AddOptionEvent(option));
        return true;
      }
      return false;
  
negative.code:   ///
    /// The [Iterable] may include [Option]s or [String]s. An `Option` created
    /// from a `String` uses that `String` for both its text and name.
    void addExclusive(Iterable<dynamic> options, {Duration delay: Duration.ZERO}) {
      Set<Option> exclusiveSet =
          options.map((o) => o is Option ? o : new Option(o)).toSet();
      exclusiveSet.forEach(_addOption);
  