from sympy import *
from spb import *
a, b, x = symbols("a b x")
max_r = 30
plot_parametric(
    x * cos(x), x * sin(x), prange(x, a, b),
    aspect="equal", use_cm=False,
    animation=True, params={a: (10, 0), b: (20, max_r)},
    title=("a={:.2f}; b={:.2f}", a, b),
    xlim=(-max_r, max_r), ylim=(-max_r, max_r)
)