private IEnumerable<IArgument> Time(ArgumentValueLookup args)
        {
            var time = DateTime.Now.ToString();

            VirtualMachine.Output.WriteLine(time);

            return new IArgument[] { new ValueArgument(time, typeof(string)) };
        }
 private IEnumerable<IArgument> Exit(ArgumentValueLookup args)
 {
     throw new ExitShellException("Bye!");
 }