code: def lock(self, connection, session):
          
          cid = id(connection)
          try:
              self.connection_handle(connection).lock(session)
          except KeyError:
              raise ConnectionNotFoundError(self.id, cid)
          else:
              if self.idle_start:
                  with self._lock:
                      self.idle_start = None
          LOGGER.debug('Pool %s locked connection %s', self.id, cid)
docs: Explicitly lock the specified connection
  
          :type connection: psycopg2.extensions.connection
          :param connection: The connection to lock
          :param queries.Session session: The session to hold the lock