message: Add getRoot/setRoot to interface
diff: @@ -34,4 +34,6 @@ export type NodeNotEmpty = NodeKv | NodeBranch;
  export type Node = NodeEmpty | NodeNotEmpty;
  export interface TrieDb extends TxDb<Uint8Array> {
  + getRoot (): Uint8Array;
  + setRoot (rootHash: Uint8Array): void;
  }
  