wp-admin/includes/import.php:37Sorts a multidimensional array by first member of each top level member.
$aarray$barrayintfunction _usort_by_first_member( $a, $b ) { return strnatcasecmp( $a[0], $b[0] );}Introduced in 2.9.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/import.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.