How to use the @polkadot/rpc-core.default function in @polkadot/rpc-core

const BN = require('bn.js');
const Rpc = require('@polkadot/rpc-core').default;
const WsProvider = require('@polkadot/rpc-provider/ws').default;
const extrinsics = require('@polkadot/extrinsics').default;
const encodeExtrinsic = require('@polkadot/extrinsics/codec/encode').default;
const encodeLength = require('@polkadot/extrinsics/codec/encode/length').default;
const Keyring = require('@polkadot/keyring').default;
const storage = require('@polkadot/storage').default;

const Encoder = new TextEncoder();
const keyring = new Keyring();
const provider = new WsProvider('ws://127.0.0.1:9944');
const api = new Rpc(provider);

async function getAccountIndex (address) {
  return api.state.getStorage([storage.system.public.accountIndexOf, address]);
}

async function transfer (keyRingFrom, addressTo, amount) {
  const accountIndex = await getAccountIndex(keyRingFrom.address());

  console.log(`Current accountIndex: ${accountIndex}`);

  // encode the call for signing
  const message = encodeExtrinsic(
    keyRingFrom.publicKey(),
    accountIndex,
    extrinsics.staking.public.transfer,
    [addressTo, amount]

const Rpc = require('@polkadot/rpc-core').default;
const WsProvider = require('@polkadot/rpc-provider/ws').default;
const provider = new WsProvider('ws://127.0.0.1:9944');
const api = new Rpc(provider);

api.chain
  .newHead((error, header) => {
    if (error) {
      console.error('error:', error);
    }

    console.log(`best #${header.blockNumber.toString()}`);
  })
  .then((subscriptionId) => {
    console.log(`subscriptionId: ${subscriptionId}`);
    // id for the subscription, can unsubscribe via
    // api.chain.newHead.unsubscribe(subscriptionId);
  })
  .catch((error) => {
    console.error('error subscribing:', error);

const BN = require('bn.js');
const Rpc = require('@polkadot/rpc-core').default;
const WsProvider = require('@polkadot/rpc-provider/ws').default;
const extrinsics = require('@polkadot/extrinsics').default;
const encodeExtrinsic = require('@polkadot/extrinsics/codec/encode/uncheckedLength').default;
const Keyring = require('@polkadot/keyring').default;
const storage = require('@polkadot/storage').default;

const Encoder = new TextEncoder();
const keyring = new Keyring();
const provider = new WsProvider('ws://127.0.0.1:9944');
const api = new Rpc(provider);

async function getAccountIndex (address) {
  return api.state.getStorage([storage.system.public.accountIndexOf, address]);
}

async function transfer (keyRingFrom, addressTo, amount) {
  const nextAccountIndex = await getAccountIndex(keyRingFrom.address());

  // encode the call for signing
  const encoded = encodeExtrinsic(
    keyRingFrom,
    nextAccountIndex,
    extrinsics.staking.public.transfer,
    [addressTo, amount]
  );

const Rpc = require('@polkadot/rpc-core').default;
const WsProvider = require('@polkadot/rpc-provider/ws').default;
const provider = new WsProvider('ws://127.0.0.1:9944');
const api = new Rpc(provider);

async function getChain () {
  return api.system.chain();
}

async function main () {
  const chain = await getChain();

  console.log('You are connected to chain:', chain);
}

main().finally(_ => process.exit());

const BN = require('bn.js');
const Rpc = require('@polkadot/rpc-core').default;
const WsProvider = require('@polkadot/rpc-provider/ws').default;
const storage = require('@polkadot/storage').default;
const provider = new WsProvider('ws://127.0.0.1:9944');
const api = new Rpc(provider);

const Alice = '5GoKvZWG5ZPYL1WUovuHW3zJBWBP5eT8CbqjdRY4Q6iMaDtZ';

console.log('You may leave this example running and start example 06 or send DOTs to ' + Alice);

api.state
  .storage([[storage.staking.public.freeBalanceOf, Alice]], (_, values) => {
    console.log(`Balance of ${Alice}: ${new BN(values[0]).toString(10)} DOTs`);
  })
  .then((subscriptionId) => {
    console.log('Balance changes subscription id:', subscriptionId);
  });

const BN = require('bn.js');
const Rpc = require('@polkadot/rpc-core').default;
const WsProvider = require('@polkadot/rpc-provider/ws').default;
const storage = require('@polkadot/storage').default;

const provider = new WsProvider('ws://127.0.0.1:9944');
const api = new Rpc(provider);

async function getAccountIndex (address) {
  return api.state.getStorage([storage.system.public.accountIndexOf, address]);
}

async function getValidators () {
  return api.state.getStorage([storage.session.public.validators]);
}

async function getBlockPeriod () {
  return api.state.getStorage([storage.timestamp.public.blockPeriod]);
}

async function main () {
  const address = '5GoKvZWG5ZPYL1WUovuHW3zJBWBP5eT8CbqjdRY4Q6iMaDtZ';
  const validators = await getValidators();