RESTSHARP: GET / POST/ DOWNLOAD and UPLOAD with and without Authentication

//GET:
var client = new RestClient("http://www.example.com/");
client.Authenticator = new HttpBasicAuthenticator("username", "password");
var request = new RestRequest(URI, Method.GET);
request.AddQueryParameter("id", customid);
var queryResult = client.Execute(request).Content;

//POST:
var client = new RestClient("http://www.example.com/");
client.Authenticator = new HttpBasicAuthenticator("username", "password");
var request = new RestRequest(URI, Method.POST);
request.RequestFormat = DataFormat.Json;
request.AddQueryParameter("id", customid);
request.AddBody(Parameters);
IRestResponse response = client.Execute(request);

//DOWNLOAD FILE:
var client = new RestClient("http://www.example.com/");
client.Authenticator = new HttpBasicAuthenticator("username", "password");
var request = new RestRequest(URI, Method.GET);
request.AddQueryParameter("id", customid);
return client.DownloadData(request);

//UPLOAD FILE:
var client = new RestClient("http://www.example.com/");
client.Authenticator = new HttpBasicAuthenticator("username", "password");
var request = new RestRequest(URI, Method.POST);
request.RequestFormat = DataFormat.Json;
request.AddQueryParameter("id", customid);
request.AddFile("file", file);
IRestResponse response = client.Execute(request);