/// <summary>
/// Sends a BAPSNet message to set an option to one of its choices.
/// </summary>
/// <param name="optionKey">The key of the option to set.</param>
/// <param name="choiceKey">The choice to use.</param>
/// <param name="index">If present and valid, the index of the option to set.</param>
public void SetChoice(OptionKey optionKey, string choiceKey, int index = ConfigCache.NoIndex)
{
var optionId = (uint)optionKey;
var choiceIndex = _cache.ChoiceIndexFor(optionId, choiceKey);
var cmd = PossiblyIndexedConfigCommand(ConfigOp.SetConfigValue, index);
Send(new MessageBuilder(cmd).Add(optionId).Add((uint)ConfigType.Choice).Add((uint)choiceIndex));
}