trasnfer.cs

using (var session = store.OpenAsyncSession())
{    
    var src = await session.LoadAsync<Account>("accounts/123-A");
    var dst = await session.LoadAsync<Account>("accounts/456-B");
    
    if(src.Blocked || dst.Blocked)
        throw new InvalidOperationException("Unable to transfer money from/to blocked accounts");
    
    if(src.Funds < 5)
        throw new InvalidOperationException("Insufficient funds");
    var coins = src.WithdrawCoins(amount);
    if (coins.Any(coin => coin.Tainted))
    {
        throw new InvalidOperationException("Unable to use tainted coins");
    }
    dst.AddCoins(coins);
    await session.SaveChangesAsync();
}