input: Write a function to automate the login process on a target website using Selenium in Python. The function should initialize a web driver, navigate to the target web page, locate and fill in the username and password fields, click the submit button, and print a success message. If the login is successful, return True; otherwise, return False. If the target website URL is empty, return None.
  assert automate_login('http://www.example.com')==True
  assert automate_login('')==None
  assert automate_login('http://www.incorrecturl.com')==False
output: def automate_login(url):
      if not url:
          return None
      
      from selenium import webdriver
      from selenium.webdriver.common.by import By
      from selenium.webdriver.common.keys import Keys
  
      driver = webdriver.Chrome()
      try:
          driver.get(url)
          username = driver.find_element(By.ID, 'username')
          password = driver.find_element(By.ID, 'password')
          submit_button = driver.find_element(By.ID, 'submit')
          
          username.send_keys('your_username')
          password.send_keys('your_password')
          submit_button.click()
          
          print("Login successful")
          return True
      except Exception as e:
          print(f"Login failed: {e}")
          return False
      finally:
          driver.quit()