wp-includes/link-template.php:2629Retrieves the previous posts page link.
string|voidfunction get_previous_posts_page_link() { global $paged; if ( ! is_single() ) { $previous_page = (int) $paged - 1; if ( $previous_page < 1 ) { $previous_page = 1; } return get_pagenum_link( $previous_page ); }}Introduced in 2.0.10. One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
string|void to string|null.verified against sourcesrc/wp-includes/link-template.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.