Magento 1.x
Mage::app()->getStore()
Magento 2
/**
* @param int|string|null|bool|\Magento\Store\Api\Data\StoreInterface $id [optional]
* @return \Magento\Store\Api\Data\StoreInterface
* @throws \Magento\Framework\Exception\NoSuchEntityException
*/
function rm_store($id = null) {
/** @var \Magento\Framework\ObjectManagerInterface $om */
$om = \Magento\Framework\App\ObjectManager::getInstance();
/** @var \Magento\Store\Model\StoreManagerInterface $manager */
$manager = $om->get('Magento\Store\Model\StoreManagerInterface');
return $manager->getStore($id);
}