input: Write a function to create a web crawler that starts from a given URL, scrapes the page content, and looks for other links within the page. The crawler should continue this process for each discovered link by following them to the next page, ensuring that each page is not revisited. The function should simulate this behavior without executing an external call or making HTTP requests.
  
  def crawl(url):
   visited = set()
   queue = [url] 
   
   while queue:
   curr = queue.pop(0)
   visited.add(curr) 
   
   # Find and process links here without making an HTTP request
   
   assert crawl('http://example.com')==None
   assert crawl('http://example2.com')==None
output: def crawl(url):
      visited = set()
      queue = [url]
      
      while queue:
          curr = queue.pop(0)
          if curr not in visited:
              visited.add(curr)
              # Simulate finding links within the page
              links = [curr + '/page1', curr + '/page2']  # Example links
              for link in links:
                  if link not in visited:
                      queue.append(link)