[-]: "UTF8.php" -> ```private``` functions without return types
[-]: "UTF8.php" -> ```private``` functions without return types

-> checked via phpstan + psalm, so no need to do the same every time on runtime

-> https://github.com/voku/portable-ascii/commit/93a8c7f3ea2ae958781d2938defe9751f10d8214#commitcomment-35107100

voku/portable-utf8