- while ,node-var ; FIXME: this is non-ANSI
- for ,n-prev = (node-prev ,node-var)
- and ,lvar = (when (valued-node-p ,node-var) (node-lvar ,node-var))
+ for ,n-prev = (when ,node-var (node-prev ,node-var))
+ and ,lvar = (when (and ,node-var (valued-node-p ,node-var))
+ (node-lvar ,node-var))
+ while ,node-var