def test_shift_removes_and_returns_first_item(self):
    c = Collection(['foo', 'bar'])
    self.assertEqual('foo', c.shift())
    self.assertEqual('bar', c.first())
def test_shift_removes_and_returns_first_item(self):
    c = Collection(['foo', 'bar'])
    self.assertEqual('foo', c.shift())
    self.assertEqual('bar', c.first())