private function _resolveService($className) {
        $serviceDependencies = $this->_serviceDependencyErrorCheck($className);
        if (empty($serviceDependencies)) {
            return $this->_instanciateService($className, []);
        } else {
            $di = [];
            foreach ($serviceDependencies as $dependency) {
                //set $di[] with all dependencies and invoke
                $di[] = $this->_resolveService($dependency);
            }
            return $this->_instanciateService($className, $di);
        }
    }