plot_parametric(
     2 * cos(u) + 5 * cos(2 * u / 3),
     2 * sin(u) - 5 * sin(2 * u / 3),
     (u, 0, 6 * pi), aspect="equal",
     colorbar_ticks_formatter=multiples_of_pi())
# Expected:
## Plot object containing:
## [0]: parametric cartesian line: (5*cos(2*u/3) + 2*cos(u), -5*sin(2*u/3) + 2*sin(u)) for u over (0, 6*pi)