public IHttpActionResult RemoveUrl(string url)
        {
            #region contracts
            if (!Regex.IsMatch(url, ""))
            {
                return(BadRequest("url is not in correct format. "));
            }
            #endregion

            UrlService urlService = new UrlService();
            {
                UrlPair urlPair = urlService.Read(url);

                if (urlPair is null)
                {
                    HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.NotFound, "Not Found");


                    return(ResponseMessage(response));
                }
                else
                {
                    urlService.Delete(urlPair);
                }

                return(Ok(urlPair));
            }
        }