wp-includes/rest-api.php:1581Determines if a given value is array-like.
$maybe_arraymixedboolfunction rest_is_array( $maybe_array ) { if ( is_scalar( $maybe_array ) ) { $maybe_array = wp_parse_list( $maybe_array ); } return wp_is_numeric_array( $maybe_array );}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/rest-api.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.