input: Write a python function to measure the time taken to load a URL.
  assert loadUrl('http://example.com')>=0
  assert loadUrl('https://www.google.com')>=0
  assert loadUrl('http://nonexistent.website')>=0
output: def loadUrl(url):
      import time
      import requests
      
      start_time = time.time()
      try:
          response = requests.get(url)
          response.raise_for_status()
      except requests.RequestException:
          pass
      end_time = time.time()
      
      return end_time - start_time