p1 = plot(cos(x) * exp(-c * x), (x, 0, 10), "f(x)",
    title="plot 1", show=False)
p2 = plot(
    (exp(-c * x), "upper limit"),
    (-exp(-c * x), "lower limit"), (x, 0, 10), {"linestyle": "--"},
    title="plot 2", xlabel="xx", ylabel="yy", show=False)
p1.append(p2[0])
print(p1)
# Expected:
## Plot object containing:
## [0]: cartesian line: exp(-x/5)*cos(x) for x over (0.0, 10.0)
## [1]: cartesian line: exp(-x/5) for x over (0.0, 10.0)
p1.show()