queue[parentIndex] = x;
        return parentIndex;
      }
      queue[index] = x;
      return index;
    }

    // About the term "aunt node": it's better to leave gender out of it, but for this the English
    // language has nothing for us. Except for the whimsical neologism "pibling" (!) which we
    // obviously could not expect to increase anyone's understanding of the code.

    /**