public function getEdge(EloquentModel $model = null, $attributes = array())
    {
        $model = ( ! is_null($model)) ? $model : $this->parent->{$this->relation};

        // Indicate a unique relation since this only involves one other model.
        $unique = true;
        return new EdgeOut($this->query, $this->parent, $model, $this->foreignKey, $attributes, $unique);
    }