public function linkTo($key, $model, $foreign): void
    {
        Relations::setRelation($this->model, $key, $model, $foreign);
    }
public function linkTo($key, $model, $foreign): void
    {
        Relations::setRelation($this->model, $key, $model, $foreign);
    }
public function linkTo ( $ key , $ model , $ foreign ) : void { Relations :: setRelation ( $ this -> model , $ key , $ model , $ foreign ) ; }
Setup relation "one to one" or "one to many"

@param  string $key
@param  string $model
@param  string $foreign

@return void
Setup relation one to one or one to many