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/schema.hpp b/src/schema.hpp
index 00586b5..6955686 100644
--- a/src/schema.hpp
+++ b/src/schema.hpp
@@ -68,6 +68,7 @@
     [[nodiscard]] virtual std::string leafrefPath(const std::string& leafrefPath) const = 0;
     [[nodiscard]] virtual std::optional<std::string> description(const std::string& location) const = 0;
     [[nodiscard]] virtual yang::Status status(const std::string& location) const = 0;
+    [[nodiscard]] virtual bool hasInputNodes(const std::string& path) const = 0;
 
     [[nodiscard]] virtual std::set<ModuleNodePair> availableNodes(const boost::variant<dataPath_, schemaPath_, module_>& path, const Recursion recursion) const = 0;
 };