1  program comma_separators.alpha {
 2      struct Foo1 {
 3          y: u8
 4      }
 5      struct Foo2::[N: u32] {
 6          y: u8
 7      }
 8      struct Foo3::[N: u32, M: address] {
 9          z: Foo2::[5],
10      }
11  
12      transition main() {
13      }
14  }