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);
}