How to use the openpgp.openpgp.keyring function in openpgp

PGP.prototype.importKeys = function(options, callback) {
        var publicKey, privateKey;

        // check passphrase
        if (typeof options.passphrase !== 'string' || !options.privateKeyArmored || !options.publicKeyArmored) {
            callback({
                errMsg: 'Importing keys failed. Not all options set!'
            });
            return;
        }

        // clear any keypair already in the keychain
        openpgp.keyring.init();
        // unlock and import private key 
        if (!openpgp.keyring.importPrivateKey(options.privateKeyArmored, options.passphrase)) {
            openpgp.keyring.init();
            callback({
                errMsg: 'Incorrect passphrase!'
            });
            return;
        }
        // import public key
        openpgp.keyring.importPublicKey(options.publicKeyArmored);

        // check if keys have the same id
        privateKey = openpgp.keyring.exportPrivateKey(0);
        publicKey = openpgp.keyring.getPublicKeysForKeyId(privateKey.keyId)[0];
        if (!privateKey || !privateKey.armored || !publicKey || !publicKey.armored || privateKey.keyId !== publicKey.keyId) {
            // reset keyring

// clear any keypair already in the keychain
        openpgp.keyring.init();
        // unlock and import private key 
        if (!openpgp.keyring.importPrivateKey(options.privateKeyArmored, options.passphrase)) {
            openpgp.keyring.init();
            callback({
                errMsg: 'Incorrect passphrase!'
            });
            return;
        }
        // import public key
        openpgp.keyring.importPublicKey(options.publicKeyArmored);

        // check if keys have the same id
        privateKey = openpgp.keyring.exportPrivateKey(0);
        publicKey = openpgp.keyring.getPublicKeysForKeyId(privateKey.keyId)[0];
        if (!privateKey || !privateKey.armored || !publicKey || !publicKey.armored || privateKey.keyId !== publicKey.keyId) {
            // reset keyring
            openpgp.keyring.init();
            callback({
                errMsg: 'Key IDs dont match!'
            });
            return;
        }

        callback();
    };

PGP.prototype.decrypt = function(ciphertext, senderKey, callback) {
        var privateKey = openpgp.keyring.exportPrivateKey(0).obj;
        senderKey = openpgp.read_publicKey(senderKey)[0];

        var msg = openpgp.read_message(ciphertext)[0];
        var keymat = null;
        var sesskey = null;

        // Find the private (sub)key for the session key of the message
        for (var i = 0; i < msg.sessionKeys.length; i++) {
            if (privateKey.privateKeyPacket.publicKey.getKeyId() === msg.sessionKeys[i].keyId.bytes) {
                keymat = {
                    key: privateKey,
                    keymaterial: privateKey.privateKeyPacket
                };
                sesskey = msg.sessionKeys[i];
                break;
            }

PGP.prototype.exportKeys = function(callback) {
        var publicKey, privateKey;

        privateKey = openpgp.keyring.exportPrivateKey(0);
        if (privateKey && privateKey.keyId) {
            publicKey = openpgp.keyring.getPublicKeysForKeyId(privateKey.keyId)[0];
        }

        if (!privateKey || !privateKey.keyId || !privateKey.armored || !publicKey || !publicKey.armored) {
            callback({
                errMsg: 'Could not export keys!'
            });
            return;
        }

        callback(null, {
            keyId: util.hexstrdump(privateKey.keyId).toUpperCase(),
            privateKeyArmored: privateKey.armored,
            publicKeyArmored: publicKey.armored
        });