Design a credit tracking service for user token balances

Credits You're building a system to track balances for the OpenAl API credit purchasing system. API users can purchase credit grants, specified by an ID, that are active at a timestamp and that let them use the API. Unused credit grant balances expire at a certain time. However, there's a kink in our system: requests can arrive out of order because our system is built on a really unstable network. For example, a request to subtract credits can arrive at the system before the request to add credits, even though the request to add credits has a lower timestamp. Your task is to implement the Credits class, which should support the following operations: • Granting credits, subtracting credits, and getting the credit balance for a user • The ability to handle requests that arrive out of order Some guidelines/hints: • Do NOT worry about memory or performance concerns. Write simple, working code. No fancy data structures are needed here. timestamp). • Subtract from grants expiring soonest first. • All timestamps can be represented as ints for simplicity and are unique (no two actions will happen at the same