input: Write a function to scrape a given website and return the HTML content. The function should use Python's `requests` and `BeautifulSoup` libraries.
  
  def scrape_website(url):
      import requests
      from bs4 import BeautifulSoup
      page = requests.get(url)
      soup = BeautifulSoup(page.text, 'html.parser')
      return soup
  
  assert str(scrape_website('https://example.com')).startswith("<html>")
  assert str(scrape_website('https://example.org')).startswith("<!doctype html>")
  assert str(scrape_website('https://example.net')).startswith("<!doctype html>")
  assert str(scrape_website('https://example.com/non-existent-page')).startswith("<!doctype html>")
  assert scrape_website('http://non-existent-website.com') is None
output: def scrape_website(url):
      import requests
      from bs4 import BeautifulSoup
      try:
          page = requests.get(url)
          if page.status_code == 200:
              soup = BeautifulSoup(page.text, 'html.parser')
              return soup
          else:
              return None
      except requests.exceptions.RequestException:
          return None