public void Add <TResult>(CommandOption option, Expression <Func <TOptions, TResult> > to) => _options[option] = PropertySelector.Do(to);
public void Add <TResult>(CommandArgument arg, Expression <Func <TOptions, TResult> > to) => _arguments[arg] = PropertySelector.Do(to);
public void Add <T>(string data, Expression <Func <TOptions, T> > to) => _data.Add(new OptionArgument(PropertySelector.Do(to), data));