def reset(self):
    'Reset the simulation.'
    self.physics.reset()
    self.physics.set_gravity(self._gravity)
    self._bodies = dict()
    self._constraints = dict()
    self._num_steps = 0
Reset the simulation.
def reset(self):
    
    self.physics.reset()
    self.physics.set_gravity(self._gravity)
    self._bodies = dict()
    self._constraints = dict()
    self._num_steps = 0