Book1 Listing 65: vup is not defined yet

[estshorter]

I think vup is not defined yet.

raytracing.github.io/books/RayTracingInOneWeekend.html

Line 2850 in 7b92650

camera cam(point3(-2,2,1), point3(0,0,-1), vup, 20, aspect_ratio);

The above should be

camera cam(point3(-2,2,1), point3(0,0,-1), vec3(0,1,0), 20, aspect_ratio);