wp-content/themes/twentysixteen/inc/back-compat.php:40Adds a message for unsuccessful theme switch.
function twentysixteen_upgrade_notice() { printf( '<div class="error"><p>%s</p></div>', sprintf( /* translators: %s: The current WordPress version. */ __( 'Twenty Sixteen requires at least WordPress version 4.4. You are running version %s. Please upgrade and try again.', 'twentysixteen' ), $GLOBALS['wp_version'] ) );}Introduced in Twenty Sixteen 1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-content/themes/twentysixteen/inc/back-compat.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.