from sympy.abc import a, b, c, d, e, f, g, s
from sympy.physics.control.lti import TransferFunction
from spb import plot_step_response
tf1 = TransferFunction(8*s**2 + 18*s + 32, s**3 + 6*s**2 + 14*s + 24, s)
tf2 = TransferFunction(s**2 + a*s + b, s**3 + c*s**2 + d*s + e, s)
plot_step_response(
    (tf1, "A"), (tf2, "B"), lower_limit=f, upper_limit=g,
    params={
        a: (3.7, 0, 5),
        b: (10, 0, 20),
        c: (7, 0, 8),
        d: (6, 0, 25),
        e: (16, 0, 25),
        # NOTE: remove `None` if using ipywidgets
        f: (0, 0, 10, 50, None, "lower limit"),
        g: (10, 0, 25, 50, None, "upper limit"),
    })