input: Write a python function to extract all hyperlinks from a given webpage using BeautifulSoup.
  assert extract_hyperlinks('http://www.example.com') == ['http://example.com/link1', 'http://example.com/link2']
  assert extract_hyperlinks('http://www.testpage.com') == ['http://testpage.com/link1', 'http://testpage.com/link2', 'http://testpage.com/link3']
output: def extract_hyperlinks(url):
      import requests
      from bs4 import BeautifulSoup
  
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
      
      hyperlinks = []
      for link in soup.find_all('a', href=True):
          hyperlinks.append(link['href'])
      
      return hyperlinks