code: function isArgVariadic(val, variadic) {
      variadic = variadic || constants_1.VARIADIC_CHAR;
      return isArg(val)
          && (val.endsWith(variadic + ']')
              || val.endsWith(variadic + '>'));
  }
docs: Checks if an argument contains variadic characters.
  
  @example [arg...] >> true
  
  @param val the value to be inspected.
  @param variadic the variadic char to check if exists.