stella multi sig

app.get('/multisig/:accf/:acct', (request, response) => {

    var pairSecond = StellarSdk.Keypair.fromSecret(request.params.accf);
    var mainPair = StellarSdk.Keypair.fromSecret(request.params.acct);

    var pairToBePaid = StellarSdk.Keypair.fromSecret("SCK3Z2STK2BQ6WT3XDUJ4MM3TUO2NOWRYJBOAJTQHBPV5EGA7YKRGFHX");

    server.loadAccount(mainPair.publicKey()).then((account) => {

        var transaction = new StellarSdk.TransactionBuilder(account)
            .addOperation(StellarSdk.Operation.payment({
                destination: pairToBePaid.publicKey(),
                asset: StellarSdk.Asset.native(),
                amount: "2" // 2000 XLM
            }))
            .addOperation(StellarSdk.Operation.setOptions({
                setFlags: 1,
                signer: {
                    ed25519PublicKey: pairSecond.publicKey(),
                    weight: 1
                },
                masterWeight: 1, // set master key weight
                lowThreshold: 1,
                medThreshold: 2, // a payment is medium threshold
                highThreshold: 2 // make sure to have enough weight to add up to the high threshold!
            }))
            .build();

        // now we need to sign the transaction with both the root and the secondaryAddress
        transaction.sign(pairSecond);
        transaction.sign(mainPair);

        server.submitTransaction(transaction)
            .then(() => {
                response.send('2 lumens sent to ' + pairToBePaid.publicKey())
            })
            .catch((err) => {
                console.log(err.response.data.extras.result_codes);
                response.send('An error ocurred!')
            });

    }).catch((err) => {
        console.log(err.response.data.extras.result_codes);
        response.send('An error ocurred!')
    });
});