printer YANG FEATURE initial implementation of YANG printer
diff --git a/src/tree_schema_internal.h b/src/tree_schema_internal.h
index 0db6a1f..8b7d66b 100644
--- a/src/tree_schema_internal.h
+++ b/src/tree_schema_internal.h
@@ -228,6 +228,18 @@
struct lysc_action **lysc_node_actions_p(struct lysc_node *node);
/**
+ * @brief Iterate over the specified type of the extension instances
+ *
+ * @param[in] ext ([Sized array](@ref sizedarrays)) of extensions to explore
+ * @param[in] index Index in the \p ext array where to start searching (first call with 0, the consequent calls with
+ * the returned index increased by 1 (until the iteration is not terminated by returning LY_ARRAY_SIZE(ext).
+ * @param[in] substmt Type of the extension (its belongins to the specific substatement) to iterate, use
+ * #LYEXT_SUBSTMT_ALL to go through all the extensions in the array
+ * @result index in the ext array, LY_ARRAY_SIZE(ext) value if not present.
+ */
+unsigned int lysp_ext_instance_iter(struct lysp_ext_instance *ext, unsigned int index, LYEXT_SUBSTMT substmt);
+
+/**
* @brief Get the covering schema module structure for the given parsed module structure.
* @param[in] ctx libyang context to search.
* @param[in] mod Parsed schema structure.