code: public function switchTo(NodeConnectionInterface $connection)
      {
          if ($connection && $connection === $this->current) {
              return;
          }
  
          if ($connection !== $this->master && !in_array($connection, $this->slaves, true)) {
              throw new \InvalidArgumentException('Invalid connection or connection not found.');
          }
  
          $connection->connect();
  
          if ($this->current) {
              $this->current->disconnect();
          }
  
          $this->current = $connection;
      }
docs: Switches the internal connection in use by the backend.
  
  Sentinel connections are not considered as part of the pool, meaning that
  trying to switch to a sentinel will throw an exception.
  
  @param NodeConnectionInterface $connection Connection instance in the pool.