def test_currencies(self):
inv = Inventory()
self.assertEqual(set(), inv.currencies())
inv = I('40 USD {1.01 CAD}, 40 USD')
self.assertEqual({'USD'}, inv.currencies())
inv = I('40 AAPL {1.01 USD}, 10 HOOL {2.02 USD}')
self.assertEqual({'AAPL', 'HOOL'}, inv.currencies())
