clean up redundant code

blockchain/block.go

@@ -60,18 +60,6 @@ func (b *Block) String() string {
 	return res
 }
 
-// HashTransactions returns a hash of the transactions in the block
-func (b *Block) HashTransactions() []byte {
-	var txHashes [][]byte
-	var txHash [32]byte
-
-	for _, tx := range b.Transactions {
-		txHashes = append(txHashes, tx.ID[:])
-	}
-	txHash = sha256.Sum256(bytes.Join(txHashes, []byte{}))
-	return txHash[:]
-}
-
 func (b *Block) Write(db db.Database, key string) error {
 	return db.Put([]byte(key), b.Serialize())
 }