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The submission includes the following changes:
Refactored the code for better OOP practice: mainly by adding classes for different types of Account and transactions;
Added more unit tests;
Additional features implemented:
* A customer can transfer between their accounts
* Change **Maxi-Savings accounts** to have an interest rate of 5% assuming no withdrawals in the past 10 days otherwise 0.1%
* Interest rates should accrue daily (incl. weekends), rates above are per-annumimplemented additional feature;