[Python] How to plot 4*sin(2*x)/cos(2*x)**3 using Sympy?

I am trying to plot the expression 4*sin(2*x)/cos3(2*x) in Sympy:

from sympy import *
from sympy.plotting import plot
x = symbols('x')
expr = 4*sin(2*x)/cos(2*x)**3
plot(expr)


But all I get is:

when it should look a bit like a horizontally-squished tangent graph:

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