validation BUGFIX keeping track of first top-level sibling
diff --git a/src/tree_data_internal.h b/src/tree_data_internal.h
index fb5e4af..0d98567 100644
--- a/src/tree_data_internal.h
+++ b/src/tree_data_internal.h
@@ -392,6 +392,14 @@
/** @} datahash */
/**
+ * @brief Update node pointer to point to the first data node of a module, leave unchanged if there is none.
+ *
+ * @param[in,out] node Node pointer, may be updated.
+ * @param[in] mod Module whose data to search for.
+ */
+void lyd_first_module_sibling(struct lyd_node **node, const struct lys_module *mod);
+
+/**
* @brief Iterate over implemented modules for functions that accept specific modules or the whole context.
*
* @param[in] tree Data tree.