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