How to use the merkle-patricia-tree/baseTrie function in merkle-patricia-tree

public async get(address: Address, blockNumber: Buffer | Tag = Tag.LATEST): Promise {
        const blockchain = this.blockchain;
        const block = await blockchain.blocks.get(blockNumber);
        const trieCopy = new Trie((blockchain as any).database.trie, block.value.header.stateRoot);
        return new Promise((resolve, reject) => {
            trieCopy.get(address.toBuffer(), (err, data)=>{
                if(err) return reject(err);
                resolve(new Account(data));
            });
        });
    }
}