plot_real_imag(sqrt(x), (x, -3-3j, 3+3j), n=100, threed=True,
     use_cm=True)
# Expected:
## Plot object containing:
## [0]: complex cartesian surface: (re(x)**2 + im(x)**2)**(1/4)*cos(atan2(im(x), re(x))/2) for re(x) over (-3.0, 3.0) and im(x) over (-3.0, 3.0)
## [1]: complex cartesian surface: (re(x)**2 + im(x)**2)**(1/4)*sin(atan2(im(x), re(x))/2) for re(x) over (-3.0, 3.0) and im(x) over (-3.0, 3.0)