def METHOD_NAME(self):
    self.sim.add(m=1., hash=c_uint32(1))
    self.sim.add(m=2., hash=c_uint32(0))
    self.assertAlmostEqual(self.sim.particles[c_uint32(0)].m, 2., delta=1e-15)
    self.assertEqual(self.sim.N_lookup, 2)
    self.sim.add(m=3., hash="jupiter")
    self.assertAlmostEqual(self.sim.particles[c_uint32(0)].m, 2., delta=1e-15)
    self.assertAlmostEqual(self.sim.particles["jupiter"].m, 3., delta=1e-15)
    self.assertEqual(self.sim.N_lookup, 3)