code: def cmd_crtsh(domain, no_cache, no_validate, verbose):
      
  
      if verbose:
          logging.basicConfig(level=logging.INFO, format='%(message)s')
  
      if not no_cache:
          homedir = pwd.getpwuid(os.getuid()).pw_dir
          requests_cache.install_cache(homedir + '/.habu_requests_cache', expire_after=3600)
  
      subdomains = set()
  
      if verbose:
          print("Downloading subdomain list from https://crt.sh ...", file=sys.stderr)
  
      req = requests.get("https://crt.sh/?q=%.{d}&output=json".format(d=domain))
  
      if req.status_code != 200:
          print("[X] Information not available!")
          exit(1)
  
      json_data = json.loads(req.text)
  
      for data in json_data:
          name = data['name_value'].lower()
          if '*' not in name:
              subdomains.add(name)
  
      subdomains = list(subdomains)
  
      if no_validate:
          print(json.dumps(sorted(subdomains), indent=4))
          return True
  
      if verbose:
          print("Validating subdomains against DNS servers ...", file=sys.stderr)
  
      answers = query_bulk(subdomains)
  
      validated = []
  
      for answer in answers:
          if answer:
              validated.append(str(answer.qname))
  
      print(json.dumps(sorted(validated), indent=4))
      return True
docs: Downloads the certificate transparency logs for a domain
      and check with DNS queries if each subdomain exists.
  
      Uses multithreading to improve the performance of the DNS queries.
  
      Example:
  
      \b
      $ sudo habu.crtsh securetia.com
      [
          "karma.securetia.com.",
          "www.securetia.com."
      ]