public async Task <string> GetToken(string code)
        {
            var request = new RestRequest("/api/token", Method.POST);
            var base64  = SpotifyHelper.Base64Encode($"{AppSettings.ClientId}:{AppSettings.ClientSecret}");

            request.AddParameter("code", code);
            request.AddParameter("redirect_uri", "https://localhost:44320/callback");
            request.AddParameter("grant_type", "authorization_code");
            request.AddHeader("Content-Type", "application/x-www-form-urlencoded");
            request.AddHeader("Authorization", $"Basic {base64}");
            IRestResponse response = await Client.ExecutePostTaskAsync <AccessTokenResponse>(request);

            return(JsonConvert.DeserializeObject <AccessTokenResponse>(response?.Content)?.AccessToken);
        }