(PHP 5 >= 5.1.0, PHP 7, PHP 8)
RecursiveIteratorIterator::beginChildren — Begin children
Is called after calling RecursiveIteratorIterator::getChildren(), and its associated RecursiveIteratorIterator::rewind().
本函数还未编写文档，仅有参数列表。
此函数没有参数。
没有返回值。
