Altcoin Inheritance

Create a class called AltCoin that extends the CryptoCoin class. The AltCoin class should have a method called getMiningDifficulty that returns a string indicating the mining difficulty of the coin. The mining difficulty should be passed in as an argument to the constructor. For example, new AltCoin('Ethereum', 2000, 'Easy').getMiningDifficulty() should return "Easy".