def METHOD_NAME(self):
    line = Line2d(0, 0, 10, 10)
    self.assertAlmostEqual(line.slope(), 1.0, delta=1e-10)
    line = Line2d(0, 0, 0, 10)
    self.assertTrue(math.isnan(line.slope()))
    line = Line2d(-10, 0, 100, 0)
    self.assertAlmostEqual(line.slope(), 0.0)