from sympy.abc import s
from sympy.physics.control.lti import TransferFunction
from spb import plot_bode, plot_bode_phase, plotgrid
tf1 = TransferFunction(
    1*s**2 + 0.1*s + 7.5, 1*s**4 + 0.12*s**3 + 9*s**2, s)
plot_bode(tf1)