repeated fix for python version

app_skellington/cli.py

@@ -83,6 +83,7 @@ class CommandTree:
         # NOTE(MG) Fix below strategizes whether to pass in 'required'
         # paremter to ArgumentParser.add_subparsers()
         # which was added in in Python3.7.
+        # Must also be written into SubMenu.create_submenu.
         func_args = {
             'dest': param_name,
             'metavar': param_name,
@@ -469,12 +470,27 @@ class SubMenu:
             help='sub-submenu help',
             description='sub-sub description')
 
+        # NOTE(MG) Fix below strategizes whether to pass in 'required'
+        # paremter to ArgumentParser.add_subparsers()
+        # which was added in in Python3.7.
+        # Must also be written into SubMenu.create_submenu.
+        func_args = {
+            'dest': var_name,
+            'metavar': var_name,
+            'required': is_required
+        }
+        if (
+            sys.version_info.major == 3
+            and sys.version_info.minor <= 6
+        ):
+            if is_required:
+                _bootstrap_logger.warn('Unable to enforce required submenu: Requires >= Python 3.7')
+            del func_args['required']
         # Turn entry into a submenu of it's own:
         # type = _SubParsersAction
         subp_node = entry_node.add_subparsers(
-            dest = var_name,
-            metavar = var_name, 
-            required = is_required)
+            **func_args
+        )
     
         submenu = SubMenu(
             self.parent,