geometry.angle(...)
attr x = geometry.angle(...)
@StartRule
Lot --> primitiveQuad(6, 4)
r(0, geometry.angle * 0.5, 0)
extrude(3)
comp(f) { top: Roof | side: Wall }
Roof --> color(0.5, 0.25, 0.15)
Wall --> color(0.75, 0.72, 0.68)