input: def crawl(url):
      """
      Create a web crawler in Python that starts from a given website URL and searches 
      for other links within the page, scraping the page content along the way. It uses 
      a breadth-first search approach to crawl through the links found on each page.
      
      >>> crawl('http://example.com')
      None
      """
output:     from urllib.parse import urljoin
      from bs4 import BeautifulSoup
      import requests
      from collections import deque
  
      def get_links(url):
          response = requests.get(url)
          soup = BeautifulSoup(response.text, 'html.parser')
          links = set()
          for a_tag in soup.find_all('a', href=True):
              full_url = urljoin(url, a_tag['href'])
              if full_url.startswith('http'):
                  links.add(full_url)
          return links
  
      visited = set()
      queue = deque([url])
  
      while queue:
          current_url = queue.popleft()
          if current_url not in visited:
              visited.add(current_url)
              print(f"Visiting: {current_url}")
              links = get_links(current_url)
              for link in links:
                  if link not in visited:
                      queue.append(link)