https://github.com/akkartik/mu/blob/main/linux/bootstrap/031transforms.cc
 1 :(before "End Types")
 2 typedef void (*transform_fn)(program&);
 3 :(before "End Globals")
 4 vector<transform_fn> Transform;
 5 
 6 :(before "End transform(program& p)")
 7 for (int t = 0;  t < SIZE(Transform);  ++t)
 8   (*Transform.at(t))(p);
 9 
10 :(before "End One-time Setup")
11 // Begin Transforms
12 // End Transforms