input: Write a python function to scrape movie titles and their release years from IMDb for a given year.
  assert scrape_movies(2020) != []
  assert isinstance(scrape_movies(2020), list)
  assert all(isinstance(movie, tuple) and len(movie) == 2 for movie in scrape_movies(2020))
output: def scrape_movies(year):
      import requests
      from bs4 import BeautifulSoup
      
      url = f'https://www.imdb.com/search/title/?year={year}&title_type=feature'
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
      
      movies = []
      for item in soup.find_all('h3', class_='lister-item-header'):
          title = item.find('a').text
          release_year = item.find('span', class_='lister-item-year').text
          movies.append((title, release_year))
      
      return movies