code: func (t *topNHeap) tryToAddRow(row *sortRow) bool {
  	success := false
  	if t.heapSize == t.totalCount {
  		t.rows = append(t.rows, row)
  		// When this row is less than the top element, it will replace it and adjust the heap structure.
  		if t.Less(0, t.heapSize) {
  			t.Swap(0, t.heapSize)
  			heap.Fix(t, 0)
  			success = true
  		}
  		t.rows = t.rows[:t.heapSize]
  	} else {
  		heap.Push(t, row)
  		success = true
  	}
  	return success
  }
docs: // tryToAddRow tries to add a row to heap.
  // When this row is not less than any rows in heap, it will never become the top n element.
  // Then this function returns false.