zipPreds :: LastNode l => LGraph m l -> BlockEnv BlockSet
zipPreds g = foldl add emptyBlockEnv (postorder_dfs g)
where add env block@(Block id _) =
zipPreds :: LastNode l => LGraph m l -> BlockEnv BlockSet
zipPreds g = foldl add emptyBlockEnv (postorder_dfs g)
where add env block@(Block id _) =