from sympy import Rational
from sympy.abc import s
from sympy.physics.control.lti import TransferFunction
from spb import *
tf1 = TransferFunction(
    4 * s**2 + 5 * s + 1, 3 * s**2 + 2 * s + 5, s)
graphics(
    nyquist(tf1, m_circles=True),
    xlabel="Real", ylabel="Imaginary",
    grid=False, aspect="equal"
)