input: Write a function to create a Python program that includes a web-page rendering feature. The function should take a URL as input and open it using the webbrowser module. If no URL is provided, it should open a default page (www.example.com).
  
  assert open_web_page("https://www.google.com")==None
  assert open_web_page("")==None
  assert open_web_page("https://www.facebook.com")==None
output: def open_web_page(url=""):
      import webbrowser
      if not url:
          url = "www.example.com"
      webbrowser.open(url)