input: Write a python function to crawl a given website and return the list of all links found.
  assert set(web_crawl("https://www.example.com")) == set(["https://www.iana.org/domains/example"])
  assert set(web_crawl("https://www.wikipedia.org")) != set()
  assert set(web_crawl("https://www.nonexistentwebsite.com")) == set()
output: def web_crawl(url):
      import requests
      from bs4 import BeautifulSoup
      from urllib.parse import urljoin
  
      try:
          response = requests.get(url)
          response.raise_for_status()
      except (requests.RequestException, requests.HTTPError):
          return []
  
      soup = BeautifulSoup(response.content, 'html.parser')
      links = set()
      
      for anchor in soup.find_all('a', href=True):
          link = urljoin(url, anchor['href'])
          links.add(link)
      
      return list(links)