The action can be function or table...(I want to normalize it...Hm...)

lua/cmp/core.lua

@@ -74,9 +74,13 @@ end
 core.on_keymap = function(keys, fallback)
   for key, action in pairs(config.get().mapping) do
     if key == keys then
+      if type(action) == 'function' then
+        return action(core, fallback)
+      else
         return action.invoke(core, fallback)
       end
     end
+  end
 
   --Commit character. NOTE: This has a lot of cmp specific implementation to make more user-friendly.
   local chars = keymap.t(keys)