code: func (h *topNChunkHeap) Less(i, j int) bool {
  	rowI := h.rowChunks.GetRow(h.rowPtrs[i])
  	rowJ := h.rowChunks.GetRow(h.rowPtrs[j])
  	return h.greaterRow(rowI, rowJ)
  }
docs: // Less implement heap.Interface, but since we mantains a max heap,
  // this function returns true if row i is greater than row j.