wrapper.dart

void main(){
  Wallet btc = BTCWallet(BTCWalletDC("", 0));
  btc.derive();
  btc.walletDC.balance;
}

// @freezed
// class WalletDC with _$WalletDC {
//   const factory WalletDC.eth(String phrase, double balance) = ETHWalletDC;
//   const factory WalletDC.btc(String phrase, double balance) = BTCWalletDC;
// }

// DC - Data Class
abstract class WalletDC {
  final String? phrase;
  final double balance;

  WalletDC(this.phrase, this.balance);
}

class ETHWalletDC extends WalletDC {
  ETHWalletDC(String? phrase, double balance) : super(phrase, balance);
}

class BTCWalletDC extends WalletDC {
  BTCWalletDC(String? phrase, double balance) : super(phrase, balance);
}

abstract class Wallet {
  WalletDC walletDC;
  Wallet(this.walletDC);

  derive();
  send();
  loadBalance();
}

class ETHWallet extends Wallet {
  ETHWalletDC ethWalletDC;
  ETHWallet(this.ethWalletDC) : super(ethWalletDC);
  
  @override
  derive() {}
  
  @override
  loadBalance() {}
  
  @override
  send() {}
}

class BTCWallet extends Wallet {
  BTCWalletDC btcWalletDC;
  BTCWallet(this.btcWalletDC) : super(btcWalletDC);
  
  @override
  derive() {}
  
  @override
  loadBalance() {}
  
  @override
  send() {}
}