@Test
public void byId() {

	Transaction t1 = MockTransaction.create("2015-01-02", "a", 123);
	Transaction t2 = MockTransaction.create("2015-01-02", "a", 123);
	Transactions transactions = new Transactions(ImmutableList.of(t1, t2));
	assertSame(t1, transactions.byId(t1.getId()));
	assertSame(t2, transactions.byId(t2.getId()));
	assertEquals(null, transactions.byId("not here"));
}