Suppose I have a parametric surface given by three functions in two variables. Moreover, this surface is imbedded in a torus like
sage: p1 = parametric_plot(( a(R + x)cos(z), a(R + y)sin(z), ay ),(p,0,2pi),(q,0,2*pi))
for some a and R.
How one can to plot a section of the surface by a plane with Sage?