get https://api.partners.sandbox.crezco.com/pay-runs/checkout/
Calling Checkout with a valid pay run ID will return a 302 redirect to the UI to allow a user to checkout.
When calling this endpoint you are expected to provide ```completeUrl``` and ```incompleteUrl``` query parameters which will be used to redirect the user back to your system following the checkout process depending on whether all batch processing is complete or not. Regardless of the URL used webhooks and/or status endpoints should always be used to obtain most accurate status information.