Function extrude 

pub fn extrude(
    model: &mut NamedModel,
    namer: &Namer,
    solid: Option<&str>,
    plane: &CoordinateSystem,
    heights: &[Scalar],
    loops: &[SweepLoop],
) -> GeopResult<BuiltBody>

Extrudes loops — the first the outer loop, counter-clockwise in plane’s (u, v), the rest holes in it, clockwise — along plane.w() through heights (see extrusion): into a solid named solid, its start cap at the first height, or, without one, into sheets. Either way round the solid comes out with its faces pointing outwards, whichever way the plane is handed.

Named after the profiles’ curves X and joints P (see Profile and [sweep]): the walls N(X), their edges on the caps N(X,start) / N(X,end), the edges between them N(P), their vertices N(P,start) / N(P,end), the caps N(start) / N(end). Through more than two heights each span’s walls and edges are N(X,q0), N(P,q0), …, and the edges and vertices at the heights between N(X,l1), N(P,l1), ….