wp-includes/class-wp-block-list.php:196Checks if current position is valid.
#[ReturnTypeWillChange] public function valid() { return null !== key( $this->blocks ); }Introduced in 5.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-block-list.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.