Simplify variant in ls_

Change-Id: I2bccf7b171f0bae619e935edba5a157a2398d877
diff --git a/src/parser.hpp b/src/parser.hpp
index 7a94919..82e7daf 100644
--- a/src/parser.hpp
+++ b/src/parser.hpp
@@ -37,7 +37,7 @@
     command_ parseCommand(const std::string& line, std::ostream& errorStream);
     void changeNode(const dataPath_& name);
     std::string currentNode() const;
-    std::set<std::string> availableNodes(const boost::optional<boost::variant<boost::variant<dataPath_, schemaPath_>, module_>>& path, const Recursion& option) const;
+    std::set<std::string> availableNodes(const boost::optional<boost::variant<dataPath_, schemaPath_, module_>>& path, const Recursion& option) const;
     Completions completeCommand(const std::string& line, std::ostream& errorStream) const;
 
 private: