input: Write a function to create a web crawler in Python that starts from a given URL, looks for other links within the page using BeautifulSoup and requests libraries, scrapes the page content, and continues crawling through discovered links. If the URL is valid and the scraper progresses, return True; otherwise, return False. For invalid URLs, return False.
  assert crawl('http://example.com')==True
  assert crawl('http://invalidurl123456.com')==False
  assert crawl('http://notrealdomainabc123.com')==False
  assert crawl('http://example.com/non-existent-page')==False
  assert crawl('')==False
output: def crawl(url):
      try:
          import requests
          from bs4 import BeautifulSoup
          response = requests.get(url)
          if response.status_code != 200:
              return False
          soup = BeautifulSoup(response.content, 'html.parser')
          links = soup.find_all('a', href=True)
          if not links:
              return False
          for link in links:
              new_url = link['href']
              if new_url.startswith('http'):
                  crawl(new_url)
          return True
      except:
          return False