### plotting a plane section in sage

Suppose I have a parametric surface given by three functions in two variables. Moreover, this surface is ~~imbedded ~~immersed in a solid torus like

sage: p1 = parametric_plot(( a*(R + x)*cos(z), a*(R + y)*sin(z), a*y ),(p,0,2*pi),(q,0,2*pi))

for some a and R.

How one can to plot a section of the surface by a plane with Sage?