def test_sd2(self):
x = '3'
y = '1.5'
self.assert_(square_of_difference(x, y) == 2.25)
def test_sd3(self):
x = '5'
y = '1.0'
self.assert_(square_of_difference(x, y) == 16.0)
def test_sd(self):
x = '1'
y = '1.0'
self.assert_(square_of_difference(x, y) == 0.0)
