input: Write a function to automate the login process in a given website using Selenium. The function should initialize a web driver, navigate to the target website, locate and fill in the username and password fields, click the submit button, and print a success message. The function should take the URL of the website, the username, and the password as inputs and return a success message if the login is successful. If the website URL is invalid, the function should print an error message.
  assert is_valid_login('http://www.example.com', 'username', 'password') == 'Login successful!'
  assert is_valid_login('http://www.invalidwebsite.com', 'username', 'password') == 'Invalid website URL!'
output: def is_valid_login(url, username, password):
      try:
          driver = webdriver.Chrome()
          driver.get(url)
          driver.find_element_by_name('username').send_keys(username)
          driver.find_element_by_name('password').send_keys(password)
          driver.find_element_by_name('submit').click()
          driver.quit()
          return 'Login successful!'
      except:
          return 'Invalid website URL!'