WordPress Version: 4.9
/**
* Checks if the current user belong to a given site.
*
* @since MU (3.0.0)
* @deprecated 3.3.0 Use is_user_member_of_blog()
* @see is_user_member_of_blog()
*
* @param int $blog_id Site ID
* @return bool True if the current users belong to $blog_id, false if not.
*/
function is_blog_user($blog_id = 0)
{
_deprecated_function(__FUNCTION__, '3.3.0', 'is_user_member_of_blog()');
return is_user_member_of_blog(get_current_user_id(), $blog_id);
}