wp-includes/pomo/translations.php:506Returns the plural form to use.
$countintint public function select_plural_form( $count ) { return 1 === (int) $count ? 0 : 1; }Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/pomo/translations.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.