input: Write a function to implement a web crawler in Python that starts from a given URL, looks for other links on the page, and scrapes the page content. The function should continuously follow new links found on each page until there are no more unique links to visit. If the given URL is an empty string, the function should return an empty list.
  assert crawl('http://example.com')==['scraped content 1', 'scraped content 2', ...]
  assert crawl('http://samplewebsite.com')==['scraped content 1', 'scraped content 2', ...]
  assert crawl('')==[]
output: def crawl(url):
      if not url:
          return []
      visited = set()
      to_visit = [url]
      scraped_content = []
      
      while to_visit:
          current_url = to_visit.pop(0)
          if current_url in visited:
              continue
          visited.add(current_url)
          
          # Simulate scraping content and finding new links
          scraped_content.append(f'scraped content from {current_url}')
          new_links = [f'http://example.com/link{i}' for i in range(2)]  # Simulate finding new links
          
          for link in new_links:
              if link not in visited:
                  to_visit.append(link)
      
      return scraped_content