docs: function validate(cmd, args, info) {
    AbstractCommand.prototype.validate.apply(this, arguments);
    var start
      , end;
  
    if(args.length !== 1 && args.length !== 3) {
      throw new CommandArgLength(cmd);
    }
  
    if(args.length > 1) {
      start = parseInt('' + args[1]);
      if(isNaN(start)) throw IntegerRange;
      args[1] = start;
      end = parseInt('' + args[2]);
      if(isNaN(end)) throw IntegerRange;
      args[2] = end;
    }
  }