docs: function validate(cmd, args, info) {
    AbstractCommand.prototype.validate.apply(this, arguments);
    var sub = info.command.sub
      , cmd = sub.cmd
      , args = sub.args
    if(('' + cmd) === Constants.SUBCOMMAND.pubsub.channels.name) {
      if(args.length > 1) {
        throw UnknownSubcommand;
      }
    }
  }