deposit.js

const account = {
  balance: 1000,
  bank: '',
  number: '',
}

const deposit = (account, value) => {
  return {
    ...account,
    balance: account.balance + value,
  }
}

deposit(account, 1000) // returns an account with balance = 2000
deposit(account, 1000) // still returns an account with balance = 2000
deposit(account, 1000) // no matter what happens, always will returns an account with balance = 2000