input: Write a python function to extract all hyperlinks from a webpage using BeautifulSoup.
  assert extract_hyperlinks('http://example.com') == ['http://example.com/about', 'http://example.com/contact']
  assert extract_hyperlinks('http://another-example.com') == ['http://another-example.com/home', 'http://another-example.com/services']
output: def extract_hyperlinks(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