wp-includes/deprecated.php:2502Checks that the taxonomy name exists.
$taxonomystringboolfunction is_taxonomy( $taxonomy ) { _deprecated_function( __FUNCTION__, '3.0.0', 'taxonomy_exists()' ); return taxonomy_exists( $taxonomy );}Introduced in 2.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/deprecated.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.