input: Write a python function to extract all links from a given URL using BeautifulSoup.
  assert get_all_links('http://example.com') == ['http://www.iana.org/domains/example']
  assert get_all_links('http://test.com') == ['http://www.example.org', 'http://www.test.org']
  assert get_all_links('http://anotherexample.com') == []
output: def get_all_links(url):
      import requests
      from bs4 import BeautifulSoup
      
      response = requests.get(url)
      soup = BeautifulSoup(response.text, 'html.parser')
      
      links = [a['href'] for a in soup.find_all('a', href=True)]
      return links