input: Write a python function to extract all URLs from a given webpage.
  assert extract_urls('https://www.example.com') == ['https://www.example.com/link1', 'https://www.example.com/link2']
  assert extract_urls('https://www.anotherexample.com') == ['https://www.anotherexample.com/page1', 'https://www.anotherexample.com/page2']
output: def extract_urls(webpage_url):
      import requests
      from bs4 import BeautifulSoup
      import urllib.parse
  
      response = requests.get(webpage_url)
      soup = BeautifulSoup(response.text, 'html.parser')
  
      urls = []
      for a_tag in soup.find_all('a', href=True):
          url = urllib.parse.urljoin(webpage_url, a_tag['href'])
          urls.append(url)
  
      return urls