int addressAt(int i) throws IOException {
      if (doSanityCheck) {
        short childrenCount = getChildrenCount();
        if (isHashedLeaf()) {
          assert i < hashPageCapacity;
        }
        else {
          boolean b = i < childrenCount || (!isIndexLeaf() && i == childrenCount);
          assert b;
        }
      }
      return getInt(indexToOffset(i));
    }
int addressAt(int i)