private function resolve($name)
    {   
        // set as resolved
        $this->resolved[$name] = true;
        
        // resolve the service
        if (is_string($this->instances[$name]) && class_exists($this->instances[$name])) 
        {
            
            $object = $this->instances[$name];

            return new $object();

        }
        elseif(is_callable($this->instances[$name]))
        {

            $callable = $this->instances[$name];

            return $callable();

        }    

        return $this->instances[$name];
    }