expr = 5 * (cos(x) - 0.2 * sin(y))**2 + 5 * (-0.2 * cos(x) + sin(y))**2
graphics(
    contour(expr, (x, 0, 2 * pi), (y, 0, 2 * pi), "z",
        rendering_kw={"cmap": "coolwarm"}),
    contour(expr, (x, 0, 2 * pi), (y, 0, 2 * pi),
        rendering_kw={"colors": "k", "cmap": None, "linewidths": 0.75},
        fill=False),
    grid=False
)
# Expected:
## Plot object containing:
## [0]: contour: 5*(-0.2*sin(y) + cos(x))**2 + 5*(sin(y) - 0.2*cos(x))**2 for x over (0.0, 6.283185307179586) and y over (0.0, 6.283185307179586)
## [1]: contour: 5*(-0.2*sin(y) + cos(x))**2 + 5*(sin(y) - 0.2*cos(x))**2 for x over (0.0, 6.283185307179586) and y over (0.0, 6.283185307179586)