input: def crawl(url: str) -> None:
      """Creates a web crawler in Python that starts from a given website and looks for other links on the page to scrape their content.
      It uses a queue to keep track of the URLs to visit and a set to keep track of visited URLs.
      >>> crawl('http://example.com')
      (Visits the page, scrapes the content, and looks for more links on the page to crawl)
      """
      visited = set()
      queue = [url] 
      
      while queue:
          curr = queue.pop(0)
          visited.add(curr) 
          response = requests.get(curr)
          
          if response.ok:
              soup = BeautifulSoup(response.text, 'html.parser')
  
              # scrape the page here 
  
              # find all the links
              links = soup.find_all('a', href=re.compile('^http')) 
              
              for link in links:
                  if link['href'] not in visited:
                      queue.append(link['href'])
output:     for link in links:
          if link['href'] not in visited:
              queue.append(link['href'])