def F(t, w, sigma, rho, beta):
    x, y, z, *_ = w
    wdot = np.zeros_like(w)
    wdot[0] = sigma * (y - x)
    wdot[1] = x * (rho-z) - y
    wdot[2] = x*y - beta*z
    return wdot

sigma, rho, beta = 10., 28., 8/3.
integrator = gi.DOPRI853Integrator(F, func_args=(sigma, rho, beta))

orbit = integrator.run([0.5,0.5,0.5,0,0,0], dt=1E-2, n_steps=1E4)
fig = orbit.plot()