code: def unlock(self):
          
          cmd = {"fsyncUnlock": 1}
          with self._socket_for_writes() as sock_info:
              if sock_info.max_wire_version >= 4:
                  try:
                      sock_info.command("admin", cmd)
                  except OperationFailure as exc:
                      # Ignore "DB not locked" to replicate old behavior
                      if exc.code != 125:
                          raise
              else:
                  helpers._first_batch(sock_info, "admin", "$cmd.sys.unlock",
                      {}, -1, True, self.codec_options,
                      ReadPreference.PRIMARY, cmd, self._event_listeners)
docs: Unlock a previously locked server.