code: function isArgVariadicRequired(val, variadic) {
      variadic = variadic || constants_1.VARIADIC_CHAR;
      return isArgRequired(val) && val.endsWith(variadic + '>');
  }
docs: Checks if an argument is variadic and also contains required tokens.
  
  @example <arg...> >> true
  
  @param val the value to inspect.
  @param variadic the char representing variadic arguments.