How to get oldValue and Current value in function

The user wants to know how to get the old and current values in a function. They mention that the value they need is in `req.variables.APPWRITE_FUNCTION_EVENT_DATA`. Currently, only the updated values are available. They mention a requested feature and provide a link to upvote it. They also mention a workaround suggestion by Steven, which can be found in this link: https://github.com/appwrite/appwrite/discussions/5615#discussioncomment-6071506. The user asks how they can get the old and current document in the cloud function.