code: def raise_or_lock(self, key, timeout):
          
          lock_path = self._get_lock_path(key)
          try:
              # Create lock file, raise exception if it exists
              fd = os.open(lock_path, os.O_CREAT | os.O_EXCL)
          except OSError as error:
              if error.errno == errno.EEXIST:
                  # File already exists, check its modification time
                  mtime = os.path.getmtime(lock_path)
                  ttl = mtime + timeout - time.time()
                  if ttl > 0:
                      raise AlreadyQueued(ttl)
                  else:
                      # Update modification time if timeout happens
                      os.utime(lock_path, None)
                      return
              else:
                  # Re-raise unexpected OSError
                  raise
          else:
              os.close(fd)
docs: Check the lock file and create one if it does not exist.