input: Write a function to create a web scraper in Python that can extract hotel reviews from TripAdvisor. The function should define the URL and headers, make a request to get the HTML, parse the HTML using BeautifulSoup, find all reviews, and extract the title and text of each review. If no reviews are found, the function should print an appropriate message.
  assert tripadvisor_scraper('<url>')==[('Stayed here twice and loved it', 'The location is perfect and the staff is very friendly.'), ('Great hotel', 'The room was clean and comfortable.'), ('Disappointing experience', 'The service was slow and the staff was unfriendly.')]
  assert tripadvisor_scraper('<url_with_no_reviews>')=='No reviews found.'
output: def tripadvisor_scraper(url):
      import requests
      from bs4 import BeautifulSoup
      
      headers = {'User-Agent': 'Mozilla/5.0'}
      response = requests.get(url, headers=headers)
      soup = BeautifulSoup(response.text, 'html.parser')
      
      reviews = soup.find_all('div', class_='review-container')
      
      if not reviews:
          return 'No reviews found.'
      
      extracted_reviews = []
      for review in reviews:
          title = review.find('span', class_='noQuotes').text
          text = review.find('p', class_='partial_entry').text
          extracted_reviews.append((title, text))
      
      return extracted_reviews