def test_non_leap_year(self):
     self.assertIs(is_leap_year(1997), False)

 def test_exceptional_century(self):
     self.assertIs(is_leap_year(2400), True)

 def test_leap_year(self):
     self.assertIs(is_leap_year(1996), True)

 def test_leap_year(self):
     self.assertTrue(is_leap_year(1996))

 def test_century(self):
     self.assertIs(is_leap_year(1900), False)

 def test_century(self):
     self.assertFalse(is_leap_year(1900))

 def test_non_leap_even_year(self):
     self.assertFalse(is_leap_year(1998))

 def test_is_leap_year(self):
     self.assertFalse(is_leap_year(2015))

 def test_is_leap_year(self):
     self.assertIs(is_leap_year(2016), True)
     self.assertFalse(is_leap_year(1994));
     self.assertIs(is_leap_year(1492), False)
     self.assertFalse(is_leap_year(1983));

 def test_leap_year(self):
     self.assertTrue(is_leap_year(abcd))