Public Shared Sub Main()
  Try
        'Create a web request for "www.msn.com".
        Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create("http://www.msn.com"), HttpWebRequest)
        
        'Get the headers associated with the request.
        Dim myWebHeaderCollection As WebHeaderCollection = myHttpWebRequest.Headers
        
        'Set the Cache-Control header.
        myWebHeaderCollection.Set("Cache-Control", "no-cache")
        
        'Get the associated response for the above request.
        Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
        
        'Print the headers of the request to console.
        Console.WriteLine("Print request headers after adding Cache-Control for first request")
        printHeaders(myHttpWebRequest.Headers)
        
   
        'Remove the Cache-Control header for the new request.
        myWebHeaderCollection.Remove("Cache-Control")
        
        'Code example for "Remove" method of "WebHeaderCollection" ends here.
        'Get the response for the new request.
        myHttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
        
        'Print the headers of the new request without the Cache-Control header.
        Console.WriteLine("Print request headers after removing Cache-Control for the new request")
        printHeaders(myHttpWebRequest.Headers)
        myHttpWebResponse.Close()
    'Catch exception if trying to remove a restricted header.
    Catch e As ArgumentException
        Console.WriteLine("Error : Trying to remove a restricted header")
        Console.WriteLine(e.Message)
    Catch e As WebException
        Console.WriteLine(e.Message)
        If e.Status = WebExceptionStatus.ProtocolError Then
            Console.WriteLine("Status Code : {0}", CType(e.Response, HttpWebResponse).StatusCode)
            Console.WriteLine("Status Description : {0}", CType(e.Response, HttpWebResponse).StatusDescription)
            Console.WriteLine("Server : {0}", CType(e.Response, HttpWebResponse).Server)
        End If
    Catch e As Exception
        Console.WriteLine(e.Message)
    End Try

End Sub