input: Write a function to scrape an online news website to get the headlines. The function should take the URL of the website as an input and print the text of all found headlines. If the website content cannot be accessed or there are no headlines found, the function should print an appropriate message.
  assert scrape_news("https://www.news.com/")=="News headline 1\nNews headline 2\nNews headline 3\n"
  assert scrape_news("https://www.unreachable.news/")=="Unable to access content."
  assert scrape_news("https://www.empty.news/")=="No headlines found."
output: def scrape_news(url):
      try:
          response = requests.get(url)
          response.raise_for_status()
          soup = BeautifulSoup(response.text, 'html.parser')
          headlines = soup.find_all('h1') + soup.find_all('h2') + soup.find_all('h3')
          if headlines:
              return "\n".join(headline.get_text() for headline in headlines)
          else:
              return "No headlines found."
      except:
          return "Unable to access content."