input: Write a function that crawls a given website to extract and return phone numbers from the webpage's content. The function should accept a website URL as an input parameter, use regular expressions to find all phone numbers in the format "XXX-XXX-XXXX", and return a list of these phone numbers. If no phone numbers are found, it should return an empty list.
  
  assert crawl_website_for_phone_numbers('www.example.com')==['123-456-7890', '987-654-3210']
  assert crawl_website_for_phone_numbers('www.nonexistentwebsite.com')==[]
  assert crawl_website_for_phone_numbers('www.anotherwebsite.com')==['555-555-5555']
  assert crawl_website_for_phone_numbers('www.emptywebsite.com')==[]
  assert crawl_website_for_phone_numbers('www.variedformatwebsite.com')==['1234567890', '987.654.3210']
output: import re
  import requests
  
  def crawl_website_for_phone_numbers(url):
      try:
          response = requests.get(url)
          response.raise_for_status()
          content = response.text
          phone_numbers = re.findall(r'\b\d{3}-\d{3}-\d{4}\b', content)
          return phone_numbers
      except:
          return []