void walkexpr(Node **np, NodeList **init);
void walkexprlist(NodeList *l, NodeList **init);
void walkexprlistsafe(NodeList *l, NodeList **init);
+void walkexprlistcheap(NodeList *l, NodeList **init);
void walkstmt(Node **np);
void walkstmtlist(NodeList *l);
Node* conv(Node*, Type*);