When printing the balance sheet, instead of only printing those with a non-zero balance, the system prints all the accounts in existence. Conventionally, only those whose balance isn't zero should be printed.
The original balance sheet printing out all accounts is lengthy and will make users lose their focus. I have rewritten the printBalanceSheet() method in Company so that only accounts with non-zero balance will be printed. By doing so, the balance sheet becomes more concise and neater.