Allow immediately executing RPC with no input

Story: https://tree.taiga.io/project/jktjkt-netconf-cli/us/189
Change-Id: I876437b798e995c4484e97b409117a2bb207e864
diff --git a/src/static_schema.hpp b/src/static_schema.hpp
index 3009d7e..0b9e59e 100644
--- a/src/static_schema.hpp
+++ b/src/static_schema.hpp
@@ -80,6 +80,7 @@
     std::set<ModuleNodePair> availableNodes(const boost::variant<dataPath_, schemaPath_, module_>& path, const Recursion recursion) const override;
     std::optional<std::string> description(const std::string& path) const override;
     yang::Status status(const std::string& location) const override;
+    bool hasInputNodes(const std::string& path) const override;
 
     /** A helper for making tests a little bit easier. It returns all
      * identities which are based on the argument passed and which can then be