createAmountIn

auto GBP = new Currency("GBP", "Great British Pound", 2);
auto amount = createAmountIn!Currency(GBP, 1000);
auto ts = cast(DateTime) amount.timestamp;

assert(is(typeof(GBP) == Currency));
assert(is(typeof(amount) == Amount));

template function returns currency

alias GBP = currency!("GBP");
// auto a = createAmountIn!Currency(GBP, 1000);
// auto money = createMoneyIn!Amount(a);
// assert(is(typeof(money) == currency));
// assert(is(typeof(a) == Amount));
// assert(is(typeof(GBP) == currency));