public virtual IRestClient AddQueryStringParameter(string key, string value)
{
Contract.Requires(!string.IsNullOrWhiteSpace(key), "The key cannot be null or empty.");
Contract.Requires(!string.IsNullOrWhiteSpace(value), "The value cannot be null or empty.");
var querySeparator = "?";
if (url.IndexOf("?", StringComparison.InvariantCulture) > -1)
{
querySeparator = "&";
}
url = string.Format("{0}{1}{2}={3}", url, querySeparator, key, value);
return this;
}