code: public function has($pCoord)
      {
          if ($pCoord === $this->currentCoordinate) {
              return true;
          }
  
          // Check if the requested entry exists in the index
          return isset($this->index[$pCoord]);
      }
docs: Whether the collection holds a cell for the given coordinate.
  
  @param string $pCoord Coordinate of the cell to check
  
  @return bool