https://www.php.net/manual/ja/reflectionfunctionabstract.isuserdefined.php
PHP: ReflectionFunctionAbstract::isUserDefined - Manual
phpmanual
https://www.php.net/manual/it/reflectionfunctionabstract.isuserdefined.php
PHP: ReflectionFunctionAbstract::isUserDefined - Manual
Checks if user defined
phpmanual