code: def open(self):
          
          if self._pid is None:
              self._pid = os.getpid()
          else:
              if os.getpid() != self._pid:
                  warnings.warn(
                      "MongoClient opened before fork. Create MongoClient only "
                      "after forking. See PyMongo's documentation for details: "
                      "http://api.mongodb.org/python/current/faq.html#"
                      "is-pymongo-fork-safe")
  
          with self._lock:
              self._ensure_opened()
docs: Start monitoring, or restart after a fork.
  
          No effect if called multiple times.
  
          .. warning:: Topology is shared among multiple threads and is protected
            by mutual exclusion. Using Topology from a process other than the one
            that initialized it will emit a warning and may result in deadlock. To
            prevent this from happening, MongoClient must be created after any
            forking.