private static async Task<String> GetHTTPResponse()
        {
            var url = "https://auth.ebay.com/oauth2/authorize?";
            var cred = RestCallProcessor.GetCred();
            var scopeList = new List<String>();
            scopeList.Add("https%3A%2F%2Fapi.ebay.com%2Foauth%2Fapi_scope%2Fsell.marketing");
            string encodedScopeList = scopeList.Aggregate((x, y) => Uri.EscapeDataString(x).ToString() + " " +                                          Uri.EscapeDataString(y).ToString());
            string uriParams = $"client_id={cred.Get(CredentialType.APP_ID)}&redirect_uri={cred.Get(CredentialType.REDIRECT_URI)}&                  response_type=code&scope={encodedScopeList}";
            var uri = url + uriParams;
            HttpClient client = new HttpClient();
            var response = await client.GetAsync(uri);
            response.EnsureSuccessStatusCode();
            return await response.Content.ReadAsStringAsync();
        }
        private async Task PageLoad()
        {
            var response = await GetHTTPResponse();
            webrowser.NavigateToString(response);
        }