function isMember($user, $group) { $members = array("john" => array("admin", "editor"), "jane" => array("editor", "viewer"), "bob" => array("viewer")); if (array_key_exists($user, $members) && in_array($group, $members[$user])) { return true; } return false; }In the above example, the function takes two parameters: $user and $group. It then checks if the $user exists in the $members array and if the $group is one of the values in the array associated with the $user key. If both conditions are true, the function returns true, indicating that the user is a member of the group. Otherwise, it returns false. Package library: This code example is not using any specific package library. Instead, it is using basic PHP functions and constructs to check if a user is a member of a group. However, there are various PHP packages and libraries available that can be used to manage user authentication and authorization, such as Laravel's built-in authentication system or Symfony's security component.