Suggest opening bracket for list keys

Change-Id: I570f11aebfd68614b7a9af80c42d9f172c64e32f
diff --git a/src/ast_handlers.hpp b/src/ast_handlers.hpp
index fede04c..dd80889 100644
--- a/src/ast_handlers.hpp
+++ b/src/ast_handlers.hpp
@@ -619,11 +619,21 @@
         if (generateMissingKeyCompletionSet(keysNeeded, parserContext.m_tmpListKeys).empty()) {
             parserContext.m_suggestions = {"]/"};
         } else {
-            parserContext.m_suggestions = {"]"};
+            parserContext.m_suggestions = {"]["};
         }
     }
 };
 
+struct suggestKeysStart_class {
+    template <typename T, typename Iterator, typename Context>
+    void on_success(Iterator const&, Iterator const&, T&, Context const& context)
+    {
+        auto& parserContext = x3::get<parser_context_tag>(context);
+
+        parserContext.m_completionSuffix = "[";
+    }
+};
+
 struct commandNamesVisitor {
     template <typename T>
     auto operator()(boost::type<T>)