code: public function getCoordinates($sorted = true)
      {
          if ($this->cellCollection == null) {
              return [];
          }
  
          if ($sorted) {
              return $this->cellCollection->getSortedCoordinates();
          }
  
          return $this->cellCollection->getCoordinates();
      }
docs: Get a sorted list of all cell coordinates currently held in the collection by row and column.
  
  @param bool $sorted Also sort the cell collection?
  
  @return string[]