Complete the following code snippet properly to process images for adding to a person group.

Parallel.For(0, PersonCount, async i => {
    Guid personId = persons[i].PersonId;
    string personImageDir = $"/path/to/person/{i}/images";
    foreach (string imagePath in Directory.GetFiles(personImageDir, "*.jpg")) {
        using ({{slot1}} t = File.OpenRead(imagePath))
        {
            await faceClient.PersonGroupPerson.{{slot2}}(personGroupId, personId, t);
        }
    }
});