input: Write a function to crawl a website and extract all phone numbers from its content. The function should return a list of phone numbers found on the website. If no phone numbers are found, it should return an empty list. The input to the function is the URL of the website, and the output is a list of phone numbers in the format of 'XXX-XXX-XXXX'.
  
  def crawl_website_for_phone_numbers(website):
      response = requests.get(website)
      phone_numbers = re.findall('\d{3}-\d{3}-\d{4}', response.text)
      return phone_numbers
  
  assert crawl_website_for_phone_numbers('www.example.com')==['123-456-7890', '987-654-3210']
  assert crawl_website_for_phone_numbers('www.no_phone.com')==[]
output: def crawl_website_for_phone_numbers(website):
      response = requests.get(website)
      phone_numbers = re.findall('\d{3}-\d{3}-\d{4}', response.text)
      return phone_numbers