Set the value for the given key in the database. If a value already exists for the key, it will be overwritten.
const db = await Deno.openKv(); await db.set(["foo"], "bar");
expireIn option can be specified to set a time-to-live
(TTL) for the key. The TTL is specified in milliseconds, and the key will
be deleted from the database at earliest after the specified number of
milliseconds have elapsed. Once the specified duration has passed, the
key may still be visible for some additional time. If the
option is not specified, the key will not expire.