code: def validate_session(self, client, session):
          
          if session:
              if session._client is not client:
                  raise InvalidOperation(
                      'Can only use session with the MongoClient that'
                      ' started it')
              if session._authset != self.authset:
                  raise InvalidOperation(
                      'Cannot use session after authenticating with different'
                      ' credentials')
docs: Validate this session before use with client.
  
          Raises error if this session is logged in as a different user or
          the client is not the one that created the session.