value_node: add combined find_or_add() and avoid duplicate names
diff --git a/value_node.h b/value_node.h
index aad62f8..9d0f5e4 100644
--- a/value_node.h
+++ b/value_node.h
@@ -16,4 +16,6 @@
struct value_node *value_node_add(void *ctx, struct value_node *parent,
const char *name, const char *value);
+struct value_node *value_node_find(struct value_node *parent, const char *name);
+struct value_node *value_node_find_or_add(struct value_node *parent, const char *name);
void value_node_del(struct value_node *node);