input: Write a python function to start an HTTP server that responds with "Hello World!!" to GET requests.
  assert start_server() == "Server started on port 8080"
  assert response_from_server("/") == "<html><body><h1>Hello World!!</h1></body></html>"
  assert response_from_server("/test") == "<html><body><h1>Hello World!!</h1></body></html>"
output: def start_server():
      import http.server
      import socketserver
      
      PORT = 8080
      
      class Handler(http.server.SimpleHTTPRequestHandler):
          def do_GET(self):
              self.send_response(200)
              self.send_header("Content-type", "text/html")
              self.end_headers()
              self.wfile.write(b"<html><body><h1>Hello World!!</h1></body></html>")
      
      with socketserver.TCPServer(("", PORT), Handler) as httpd:
          print("Server started on port", PORT)
          httpd.serve_forever()
  
      return "Server started on port 8080"
  
  def response_from_server(path):
      import urllib.request
      
      url = f"http://localhost:8080{path}"
      with urllib.request.urlopen(url) as response:
          return response.read().decode('utf-8')