public function lastKey()
    {
        $keys = AccessHelper::collectionKeys($this->data);

        if (empty($keys) || end($keys) === false) {
            return null;
        }

        return end($keys);
    }
public function lastKey()
    {
        $keys = AccessHelper::collectionKeys($this->data);

        if (empty($keys) || end($keys) === false) {
            return null;
        }

        return end($keys);
    }
public function lastKey ( ) { $ keys = AccessHelper :: collectionKeys ( $ this -> data ) ; if ( empty ( $ keys ) || end ( $ keys ) === false ) { return null ; } return end ( $ keys ) ; }
Evaluate an expression and return the last key
@return mixed
Evaluate an expression and return the last key