wp-includes/formatting.php:3725Helper function to convert hex encoded chars to ASCII.
$matchesarraystringfunction _wp_iso_convert( $matches ) { return chr( hexdec( strtolower( $matches[1] ) ) );}Introduced in 3.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/formatting.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.