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 in the default web browser. If the URL is empty, return a message indicating that the URL is required.
  
  def render_web_page(url):
      if url == "":
          return "URL is required"
      import webbrowser
      webbrowser.open(url)
  
  assert render_web_page("www.example.com")==None
  assert render_web_page("")=="URL is required"
output: def render_web_page(url):
      if url == "":
          return "URL is required"
      import webbrowser
      webbrowser.open(url)