wp-includes/class-wpdb.php:815Makes private properties check-able for backward compatibility.
$namestringbool public function __isset( $name ) { return isset( $this->$name ); }Introduced in 3.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wpdb.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.