input: Write a python function to extract the list of programming languages from the given HTML.
  assert extract_languages('<html><head><title>Top 5 Programming Languages</title></head><body><ul><li>Python</li><li>Java</li><li>JavaScript</li><li>C#</li><li>C++</li></ul></body></html>') == ['Python', 'Java', 'JavaScript', 'C#', 'C++']
  assert extract_languages('<html><head><title>Top Programming Languages</title></head><body><ul><li>Ruby</li><li>Go</li><li>Swift</li><li>PHP</li><li>Kotlin</li></ul></body></html>') == ['Ruby', 'Go', 'Swift', 'PHP', 'Kotlin']
  assert extract_languages('<html><head><title>Languages</title></head><body><ul><li>HTML</li><li>CSS</li></ul></body></html>') == ['HTML', 'CSS']
output: def extract_languages(html):
      from bs4 import BeautifulSoup
      soup = BeautifulSoup(html, 'html.parser')
      return [li.text for li in soup.find_all('li')]