def continual_update(self, *args, **kwargs):
    if hasattr(self, 'moving_particles'):
        dt = self.frame_duration
        for p in self.moving_particles:
            accel = self.field_at_point(p.get_center())
            p.velocity = (p.velocity + (accel * dt))
            p.shift((p.velocity * dt))
def continual_update(self, *args, **kwargs):
    if hasattr(self, 'moving_particles'):
        dt = self.frame_duration
        for p in self.moving_particles:
            accel = self.field_at_point(p.get_center())
            p.velocity = (p.velocity + (accel * dt))
            p.shift((p.velocity * dt))