def test_wide_angle_backwards2(self):
     angle = angle_between(self._d, self._b)
     self.assertAlmostEqual(pi, angle)
 def test_wide_angle_forwards(self):
     angle = angle_between(self._a, self._c)
     self.assertAlmostEqual(pi, angle)
 def test_angle_forwards(self):
     angle = angle_between(self._a, self._b)
     self.assertAlmostEqual(pi/2, angle)
 def test_angle_backwards2(self):
     angle = angle_between(self._c, self._d)
     self.assertAlmostEqual(pi/2, angle)
 def test_angle_self(self):
     angle = angle_between(self._a, self._a)
     self.assertEqual(0, angle)