input: Write a python function to extract all hyperlinks from a given URL using BeautifulSoup.
  assert 'https://www.example.com' in get_links('https://www.example.com')
  assert 'https://www.wikipedia.org' in get_links('https://www.wikipedia.org')
  assert 'https://www.python.org' in get_links('https://www.python.org')
output: def get_links(url):
      import requests
      from bs4 import BeautifulSoup
  
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
      
      links = []
      for a_tag in soup.find_all('a', href=True):
          links.append(a_tag['href'])
      
      return links