code: func StoreChtRoot(db ethdb.Database, sectionIdx uint64, sectionHead, root common.Hash) {
  	var encNumber [8]byte
  	binary.BigEndian.PutUint64(encNumber[:], sectionIdx)
  	db.Put(append(append(chtPrefix, encNumber[:]...), sectionHead.Bytes()...), root.Bytes())
  }
docs: // StoreChtRoot writes the CHT root associated to the given section into the database