Model within a model

Is it possible to include a model in the '__construct' and do the same with the other model?

PHP Code:

class Users_model extends \App\Models\BaseModel {

    function __construct()
    {
        // Call the Model constructor
        parent::__construct();
 $this->Settings = model('Settings_model');
    }
} 


PHP Code:

class Settings_model extends \App\Models\BaseModel {

    function __construct()
    {
        // Call the Model constructor
        parent::__construct();
 $this->Users = model('Users_model');
    }
} 


When I do this, I always get a 503 Service Temporarily Unavailable error. Is there a workaround for this?

because it will create infinite loop. like picture in picture in two mirror sided each other..