{"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"//"}]}
    // which means we don't want codegen_units[0..N] (the already big ones)
    // Why merge into codegen_units[N-1]? We want CGUs to have similar sizes,
    // getting any bigger, if we can avoid it. When we have more than N CGUs