how to borrow iterator `items` for distinct type?

[shirleyquirk]

<https://github.com/nim-lang/Nim/issues/21476> for the compiler crash

iterators cant be borrowed, you'll need to manually
    
    
    iterator items(a: A): uint8 =
      for i in cast[array[4,uint8]](a):
        yield i
    
    
    Run