private SlashCommandResponse(SlackCommandResponseType responseType, string responseText,
                              params SlashCommandReponseAttachment[] attachments)
 {
     ResponseType = responseType.ToApiString();
     ResponseText = responseText;
     Attachments  = attachments;
 }
        public static string ToApiString(this SlackCommandResponseType enumVal)
        {
            switch (enumVal)
            {
            case SlackCommandResponseType.InChannel:
                return("in_channel");

            case SlackCommandResponseType.Ephemeral:
                return("ephemeral");

            default:
                throw new ArgumentOutOfRangeException(nameof(enumVal), enumVal.ToString());
            }
        }