input: Write a function to create a web crawler in Python that starts from a given URL and looks for other links within the page, then scrapes the page content. The function should return a list of visited URLs.
  
  def crawl(url):
      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'])
                      
      return list(visited)
  
  assert crawl('http://example.com')==['http://example.com']
  assert crawl('http://example.com/page1')==['http://example.com/page1', 'http://example.com/page2']
output: def crawl(url):
      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')
  
              # 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'])
                      
      return list(visited)