other FEATURE add ly_set_dup() function
diff --git a/src/libyang.h b/src/libyang.h
index 486c8f8..d915b9d 100644
--- a/src/libyang.h
+++ b/src/libyang.h
@@ -1001,6 +1001,14 @@
struct ly_set *ly_set_new(void);
/**
+ * @brief Duplicate the existing set.
+ *
+ * @param[in] set Original set to duplicate
+ * @return Duplication of the original set.
+ */
+struct ly_set *ly_set_dup(const struct ly_set *set);
+
+/**
* @brief Add a ::lyd_node or ::lys_node object into the set
*
* Since it is a set, the function checks for duplicity and if the
@@ -1177,6 +1185,7 @@
LYVE_INRESOLV, /**< no resolvents found (schema) */
LYVE_INSTATUS, /**< invalid derivation because of status (schema) */
LYVE_CIRC_LEAFREFS,/**< circular chain of leafrefs detected (schema) */
+ LYVE_CIRC_FEATURES,/**< circular chain of features detected (schema) */
LYVE_CIRC_IMPORTS, /**< circular chain of imports detected (schema) */
LYVE_CIRC_INCLUDES,/**< circular chain of includes detected (schema) */
LYVE_INVER, /**< non-matching YANG versions of module and its submodules (schema) */