input: def crawl(url):
      """ Starts a web crawler at the given url, crawls through the links found on the page,
      and scrapes the content of each page. The crawler uses BFS to explore the links.
      
      Example:
      >>> crawl('http://example.com')
      No Output Type Specified (Set output to None if no expected output)
      """
output:     from collections import deque
      import requests
      from bs4 import BeautifulSoup
  
      visited = set()
      queue = deque([url])
  
      while queue:
          current_url = queue.popleft()
          if current_url in visited:
              continue
          visited.add(current_url)
  
          try:
              response = requests.get(current_url)
              response.raise_for_status()
          except requests.RequestException:
              continue
  
          soup = BeautifulSoup(response.text, 'html.parser')
          # Scrape content here (e.g., print or store soup.text)
  
          for link in soup.find_all('a', href=True):
              next_url = link['href']
              if next_url.startswith('http'):
                  queue.append(next_url)
              elif next_url.startswith('/'):
                  queue.append(current_url + next_url)
              else:
                  queue.append(current_url + '/' + next_url)