public function get(AbstractModel $model)
    {
        if (! $this->repo->isModel($model)) {
            throw new InvalidArgumentException(
                sprintf('Model must be %s, was %s', $this->repo->getModelClass(), get_class($model))
            );
        }

        if ($this->map->contains($model)) {
            return $this->map[$model];
        } else {
            return $this->map[$model] = new Links($model);
        }
    }