static concat(var_args) {
    let result = '';

    /**
     * @param {!SafeStyleSheet|!Array<!SafeStyleSheet>}
     *     argument
     */
    const addArgument = argument => {
      if (Array.isArray(argument)) {
        argument.forEach(addArgument);
      } else {
        result += SafeStyleSheet.unwrap(argument);
      }
    };

    Array.prototype.forEach.call(arguments, addArgument);
    return SafeStyleSheet.createSafeStyleSheetSecurityPrivateDoNotAccessOrElse(
        result);
  }
Creates a new SafeStyleSheet object by concatenating values.
@param {...(!SafeStyleSheet|!Array<!SafeStyleSheet>)}
    var_args Values to concatenate.
@return {!SafeStyleSheet}
@deprecated Use `safevalues.concatStyleSheets` instead.