Define a non-member function that creates and returns an account as a combination of two given accounts. Set this new account's balance as the total balance of the two given accounts and its interest rate as a higher one of the two given accounts. For example, if account1 has the balance $2500 and the interest rate 0.045, and account2 has the balance $500 and the interest rate 0.02, the new created account then has the balance $3000 and the interest rate 0.045.