code: func (cur *blockCursor) nextBlock() bool {
  	if cur.buf.key == nil {
  		return false
  	}
  
  	cur.base = binary.BigEndian.Uint64(cur.buf.key) / cur.n
  	return true
  }
docs: // nextBlock moves the cursor to the next block.
  // Returns true if another block exists, otherwise returns false.