src/Controller/PickupController.php
protected function getCalculator(string $shippingMethod): CalculatorInterface
    {
        $method = $this->getMethod($shippingMethod);

        if ($method === null) {
            return false;
        }

        /** @var CalculatorInterface $calculator */
        $calculator = $this->calculatorRegistry->get($method->getCalculator());

        return $calculator;
    }
protected function getCalculator(string $shippingMethod): CalculatorInterface
    {
        $method = $this->getMethod($shippingMethod);

        if ($method === null) {
            return false;
        }

        /** @var CalculatorInterface $calculator */
        $calculator = $this->calculatorRegistry->get($method->getCalculator());

        return $calculator;
    }
Retrieve Shipping Method Calculator

@param string $shippingMethod
@return CalculatorInterface|bool