def test_get_inverse(self):
     x = TimeSeries([
         (datetime.date(2001, 12, 31), 1),
         (datetime.date(2002, 12, 31), 2),
         (datetime.date(2003, 12, 31), 5),
     ])
     y = x.get_inverse()
     self.assertEqual(y.get(), [
         (datetime.date(2001, 12, 31), 1.0),
         (datetime.date(2002, 12, 31), 0.5),
         (datetime.date(2003, 12, 31), 0.2),
     ])
 def test_get_inverse(self):
     x = TimeSeries([
         (datetime.date(2001, 12, 31), 1),
         (datetime.date(2002, 12, 31), 2),
         (datetime.date(2003, 12, 31), 5),
     ])
     y = x.get_inverse()
     self.assertEqual(y.get(), [
         (datetime.date(2001, 12, 31), 1.0), 
         (datetime.date(2002, 12, 31), 0.5),
         (datetime.date(2003, 12, 31), 0.2),
     ])