input: Write a python function to create a simple HTTP server that responds with "Hello, World!" on the root URL.
  assert test_http_server_response("http://localhost:8080")=="Hello, World!"
output: def run_server():
      from http.server import HTTPServer, BaseHTTPRequestHandler
  
      class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
          def do_GET(self):
              if self.path == '/':
                  self.send_response(200)
                  self.send_header('Content-type', 'text/plain')
                  self.end_headers()
                  self.wfile.write(b'Hello, World!')
  
      httpd = HTTPServer(('localhost', 8080), SimpleHTTPRequestHandler)
      httpd.serve_forever()