- convertToStripeObject — Converts a response from the Stripe API to the corresponding PHP object.
- currentTimeMillis — Returns UNIX timestamp in milliseconds.
- isList — Whether the provided array (or other) is a list rather than a dictionary.
- objectsToIds — Recursively goes through an array of parameters. If a parameter is an instance of ApiResource, then it is replaced by the resource's ID.
- secureCompare — Compares two strings for equality. The time taken is independent of the number of characters that match.