New creates a trie with an existing root node from db.

NewDatabase creates a new trie database to store ephemeral trie content before its written out to disk or garbage collected.

NewDatabaseWithCache creates a new trie database to store ephemeral trie content before its written out to disk or garbage collected.

NewDifferenceIterator constructs a NodeIterator that iterates over elements in b that are not in a.

NewIterator creates a new key-value iterator from a node iterator.

NewSecure creates a trie with an existing root node from a backing database and optional intermediate in-memory node pool.

读数据从oldDB中，数据写入，写到newDB中.

NewUnionIterator constructs a NodeIterator that iterates over elements in the union of the provided NodeIterators.

数据恢复从oldDB中读取数据，数据存储使用writeDB.

emptyRoot is the known root hash of an empty trie.

Database is an intermediate write layer between the trie data structures and the disk database.

Iterator is a key-value trie iterator that traverses a Trie.

MissingNodeError is returned by the trie functions (TryGet, TryUpdate, TryDelete) in the case where a trie node is not present in the local database.

SecureTrie wraps a trie with key hashing.

Trie is a Merkle Patricia Trie.

NodeIterator is an iterator to traverse the trie pre-order.

LeafCallback is a callback type invoked when a trie operation reaches a leaf node.