public function getMachine(Smalldb $smalldb, string $type)
	{
		if (isset($this->machine_type_cache[$type])) {
			return $this->machine_type_cache[$type];
		} if (!$this->initialized) {
			throw new InitializationException("Backend not initialized.");
		} else {
			$m = $this->machine_type_cache[$type] = $this->createMachine($smalldb, $type);
			if ($m && $this->debug_logger) {
				$m->setDebugLogger($this->debug_logger);
				$this->debug_logger->afterMachineCreated($this, $type, $m);
			}
			return $m;
		}
	}