code: public function getConnectionByCommand(CommandInterface $command)
      {
          if (!$this->current) {
              if ($this->strategy->isReadOperation($command) && $slave = $this->pickSlave()) {
                  $this->current = $slave;
              } else {
                  $this->current = $this->getMasterOrDie();
              }
  
              return $this->current;
          }
  
          if ($this->current === $master = $this->getMasterOrDie()) {
              return $master;
          }
  
          if (!$this->strategy->isReadOperation($command) || !$this->slaves) {
              $this->current = $master;
          }
  
          return $this->current;
      }
docs: {@inheritdoc}