protected static function getEdgeItself(
        ParticleInterface $particle, 
        array $pack,
        string $name,
        Direction $direction,
        bool $singular = false
        ): array
    {
        // $name = strtolower($name); // this is now taken care of beforehand.
        $direction = (string) $direction;
        $cargo = $pack[$direction];
        $haystack = $singular ? "callable_edge_singularLabel_class_pairs" : "callable_edge_label_class_pairs";
        $edges = $particle->edges()->$direction($cargo->$haystack[$name]);
        return array_values(iterator_to_array($edges));
    }