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/ast_commands.cpp b/src/ast_commands.cpp
index 5b99c6a..fa2b56c 100644
--- a/src/ast_commands.cpp
+++ b/src/ast_commands.cpp
@@ -51,3 +51,8 @@
 {
     return this->m_path == other.m_path;
 }
+
+bool exec_::operator==(const exec_& other) const
+{
+    return this->m_path == other.m_path;
+}