code: protected function guessNode($slot)
      {
          if (!$this->pool) {
              throw new ClientException('No connections available in the pool');
          }
  
          if ($this->slotmap->isEmpty()) {
              $this->buildSlotMap();
          }
  
          if ($node = $this->slotmap[$slot]) {
              return $node;
          }
  
          $count = count($this->pool);
          $index = min((int) ($slot / (int) (16384 / $count)), $count - 1);
          $nodes = array_keys($this->pool);
  
          return $nodes[$index];
      }
docs: Guesses the correct node associated to a given slot using a precalculated
  slots map, falling back to the same logic used by Redis to initialize a
  cluster (best-effort).
  
  @param int $slot Slot index.
  
  @return string Connection ID.