public MementoToken Deposit(int amount)
{
_balance += amount;
var m = new MementoToken(_balance);
_changes.Add(m);
_current++;
return(m);
}
public MementoToken Restore(MementoToken token)
{
if (token != null)
{
_balance = token.Balance;
_changes.Add(token);
return(token);
}
return(null);
}