code: def prepend_http(url):
      
      url = url.lstrip()
      if not urlparse(url).scheme:
          return 'http://' + url
      return url
docs: Ensure there's a scheme specified at the beginning of a url, defaulting to http://
  
      >>> prepend_http('duckduckgo.com')
      'http://duckduckgo.com'